DIRECTORY OF MATERIALS

Materials for construction

Plastics

PVC

This is a particularly versatile and workable plastic, used extensively in architectural model-making. The type featured almost exclusively in this book is more properly termed ‘foamed PVC’ and goes by the brand names Palight, Foamalux or Foamex, depending upon where it comes from. The initials PVC stand for polyvinyl chloride. Foamed PVC is obtainable from specialist suppliers of plastics, shops selling display materials and some model shops. Price varies according to thickness and brand, but an 8ft × 4ft sheet of the thinnest (1mm), for example, averages at £13. It can be used in place of card for any form of building and is especially suited for finely detailed cutting. It can be embossed or scored lightly as a surfacing material, or used as a waterproof material for mould boxes.

Foamed PVC is most commonly stocked in pure white, but a range of colours is available. It also comes in many thicknesses, from 1mm to as much as 18mm. It consists of a smooth, slightly shiny outer surface with a less dense interior; hence it is very light for something so relatively strong. It is so easy to cut that even 10mm plastic can be managed eventually, cutting from both sides with a scalpel (and certainly with a Stanley knife). Edges can be sanded to a sharp finish with no fuzzing (unlike cardboard). It can be carved, but if the interior is exposed the surface will be slightly porous and ‘pithy’ and will need to be filled if any smoothness is required. Being a plastic, it is unaffected by humidity and will not absorb water. It is also unaffected by a number of solvents, including white spirit and acetone. This material is particularly resistant to any form of warping, even if left out in the sun. This rigidity is mainly due to its layered composition, acting like a cross-strutted girder. Thinner sheets can be bent into smooth curves but need to be firmly glued in place (top and bottom), otherwise they will revert.

Because cut edges are slightly porous, gluing works perfectly with cyanoacrylate (superglue), producing a virtually

unbreakable bond. But if mistakes are made there is a special ‘debonder’ that you can buy for superglue which softens it and allows you to take the materials apart. If you can get hold of pure acetone (often from a good pharmacy) this will work just as well.

If PVC is given a spray coat of Simoniz primer even thin paints can be used to paint it. It won’t absorb like soft card so some watercolour effects are out, but if these are desired then it is simple enough to spray-mount watercolour paper onto it.

Styrene

This is a versatile plastic available in many forms. It is ideal as a constructional material for particularly fine or delicate forms and its bending properties make it more suitable for curved elements. It can be found in suppliers of plastics and some model shops and is relatively cheap.

This is polystyrene, similar to the more familiar white packaging material but unexpanded in this case and usually referred to as just styrene to differentiate it.

It is harder to cut than PVC, because it is denser, but it is available in thicknesses down to 0.13mm, which is translucently thin. Thicknesses up to 1mm can still be cut with a knife fairly easily, but foamed PVC is a better option in this case. Its slight brittleness (compared to foamed PVC) can be used to advantage because it can be scored and snapped for a clean break. Often the surface will be matt on one side and glossier on the other. White is most common, but it is also available in black and a range of colours. It is also available in a seemingly infinite variety of rods, tubes, strips and sections (for example, ‘L’, ‘H’ and ‘T’ sections) and also a clear sheet version which is softer but less crystal clear than acetate.

Styrene bonds well with superglue, although if the styrene is very thin the glue will make it buckle. For a cleaner form of gluing there is a special solvent designed for styrene which effectively melts the two surfaces together. Since this solvent is water-thin, it can be brushed into a joint while the two parts are held in place and bonding happens almost immediately. This is a definite advantage when one has to glue a long curved strip, for example, doing it in carefully positioned stages and where it is difficult to apply glue to the whole strip at once. Styrene is much more bendable than foamed PVC, especially if heat is used to form a shape. For this reason, it is commonly used in vacuum forming.

ABS

This is a tougher form of styrene, often found in model shops as preformed strips and shapes. These can be useful for stronger, load-bearing construction, or as an alternative to PVC or styrene where more heat-resistance might be needed, for example under hot lights.

ABS is short for acrylonitrile butadiene styrene. It is the plastic that most people think of as plastic and is the stuff of computer housings, mobile phones and so on. It is tough, although its hardness varies with the make, and it is heat resistant. Consequently, it’s not so effective as a model material because it is less easy to cut or shape, while durability in model-making isn’t necessarily a major issue. It can be glued most effectively with superglue or plastic solvent.

Acetate

This is a thin, glass-clear sheet plastic which can be found in model shops, art and graphics suppliers or photocopy shops. An A4 sheet can cost as little as £0.20, depending upon the thickness. It is useful to represent glass in model windows, to suggest the surface of water, or (when photocopied or inkjet printed) to represent gauzes, fine mesh or translucent curtains. Acetate intended for printing is treated on one side to accept ink, which gives it a slightly grainy appearance.

A favourite for model window panes, acetate does the job well as long as the right thickness is chosen for the size. For anything bigger than 5 × 5cm square in the model it is best to use a 0.5 thickness, for example. Superglue (applied very carefully via the end of a cocktail stick and then only in strategic spots) is the best for gluing it. But this brings another drawback. Unless it’s very minimally dosed, the fumes from the superglue will ‘fog’ the acetate in places. Either one has to be very careful, or apply a coat of clear varnish to the acetate afterwards which should eliminate much of the fogging. As an alternative, you could use slivers of double-sided tape to attach the acetate to the frame. These will hold well enough even for a permanent model under normal conditions.

There are alternatives to acetate for building transparent constructions, for example clear styrene, clear PVC and HIPS (high-impact polystyrene). Not quite as crystal-clear as acetate, they’re much softer and gluing is apparently easier. They may be less likely to ‘fog’ than acetate, as well as being less brittle and easier to cut. For more rigid, see-through constructions, acrylic glass is more suitable, usually available in thicknesses upwards from 1mm. A special solvent or clear glue is necessary for bonding parts together cleanly.

Polypropylene

This can be found in ‘frosted’ sheet form (usually in 0.5mm or 1mm thicknesses) in graphics suppliers, model and hobby shops. It is particularly useful for representing frosted glass, large flat gauzes or BP (back projection) screens in a model. It is flexible and will cut easily and cleanly with a knife. The surface is extremely slippery, so it is advisable either to lay tape down and cut through that or use a good non-slip ruler. Polypropylene poses a problem to glue and even superglue will not take well to it. The best options are either to slot it into some form of supporting structure without gluing, or, when used to convey frosted windows, to tack it with thin strips of double-sided tape where these can be hidden. 1mm polypropylene is rigid enough to stand up on its own without requiring much support and may only need to be held in place at the sides. A range of colours is usually available and these can be quite rich even though the surface is frosted.

Foam

Styrofoam

Styrofoam is a rigid foam which is ideal for carving and sanding, being a fine-celled, extruded version of polystyrene. It has long been popular in film and theatre workshops even for fairly detailed decorative work (in the UK, styrofoam refers to the finer, blue material rather than the more common white packaging material). It can be bought from builders’ merchants (because it is manufactured as an insulation material), but is also available in other thicknesses from good model or hobby shops. The average price for a 600 × 1,250mm sheet of 25mm blue styrofoam, for example, is £10 (this is the form it commonly comes in at builders’ merchants). It is extremely useful: as a constructional material for thick forms; as a shaping material which can be easily carved, sanded (for example, for rocks and landscapes); or as thin sheet which can be textured and used as surfacing.

This highly versatile form-making material comes in different colour versions, which differ from each other mainly in density. The blue type, also referred to sometimes as Roofmate from an earlier brand name, is the most common. The pink type is slightly denser and sands to a finer finish, while the white variety is denser and finer still. This is quite expensive compared to the standard blue. Styrofoam is properly named ‘extruded polystyrene’ as opposed to the common ‘expanded polystyrene’ used as packaging. Its cells are much smaller, therefore it is denser and more robust than the expanded type.

Styrofoam is very easy to cut with a knife and to sand because of its rigidity. Once smooth, the surface can be coated with polyfilla or similar, and this can then be sanded to an eggshell finish if required. If the covering is combined with a mesh or fabric (as with fibreglass resin and matting), it results in a very strong, durable form. But resin will dissolve the surface of styrofoam (as will epoxy fillers, most spray paints and many glues), so before laminating in fibreglass the form’s surface needs to be thoroughly sealed with a water-based filler. Shellac, a natural sealant, will also do this well.

The best glues to use are water-based, for example PVA will glue styrofoam if the surfaces to be glued are flush. If not, it may be better to use something like polyfilla or a gap-filling adhesive. Scenic workshops favour using a two-part expanding polyurethane foam to bond pieces together where a greater amount of gap-filling is required. The advantage of this is that the bond ends up much the same consistency as the styrofoam, making carving much easier.

Polyurethane foam

For the qualities of the special type of polyurethane foam found in Kapa-line foamboard look under ‘Card’ below (in addition to Chapter 2). Other forms of rigid polyurethane foam are in common use and come in sheets with a variety of densities. Some tend to be very crumbly and unpleasant to work with, while others are so dense they can only be shaped with machine tools. Extra care needs to be taken when sanding these types of polyurethane foam because the dust is abrasive and shouldn’t be breathed in or get into the eyes!

Plastazote

This is a flexible, rubber-like sheet foam produced in a wide variety of thicknesses, densities and colours. It can usually only be obtained from specialist suppliers of foam rubber, but hobby shops commonly stock small and colourful sheets of a thinner, finer version. It is useful as a constructional material for lightweight, flexible forms, but can also be used to clad surfaces. It slices well with the knife but cannot be sanded. For gluing, a synthetic rubber contact adhesive such as Evo-Stik Impact is recommended. This can provide a very tough bond that is even effective for piecing sections together edge to edge. Superglue can work very well with the thinner ‘hobby’ versions. Plastazote is resistant to many things, certainly water. It contracts with heat and will do so very quickly under the heat gun. It will respond to a certain amount of heat-bending in this way.

Reticulated foams

One of these is featured as a useful material for making foliage, illustrated in Chapter 4. These foams are composed of a network of filaments, which are all that remains of the bubbles formed during the foaming process. They are manufactured principally as industrial filters. Sheets (in various cell sizes) can be found in good model shops, especially those catering for architectural model-making. The foam is a favourite for making small-scale trees.

Metal

Sheet metal

Small, thin sheets of brass, copper or aluminium can be commonly found in model shops. Cutting these is relatively easy by scoring with a knife and then bending (although copper will need more bending). Buying brass sheet in the form of sculptor’s shim is more economical, averaging £7 for a 160mm × 2.5m roll. This is normally 0.1mm thickness and is suitable for the work illustrated in Chapter 4. If used as cladding, Spray Mount or double-sided tape can work for gluing (although the surface needs to be thoroughly cleaned and keyed first using wire wool). Otherwise, use a stronger contact adhesive. The thin aluminium foil from food containers is a good source for cladding small areas.

Rods

This is available in a range of solid sections and tubes, whether round or square. Brass is the most convenient metal for soldering. Rods up to a certain thickness can be easily cut with a scalpel by scoring and breaking. Aluminium is usually available in larger gauges but this is not as easy to solder.

Piano wire

This is a fine, hard wire sold in straight lengths. Being steel, it keeps its shape well but can be bent using pliers if needed. Piano wire is most useful for hanging elements in a model, more precise than thread or nylon.

Aluminium wire and florist’s wire

The most versatile form of wire is aluminium because it is very soft. Sculptors prefer it for the creation of armatures and a good sculpture supplier will sell a variety of thicknesses. It will also endure repeated bending, which is why it’s commonly used for stop-motion puppet armatures. So-called ‘florist’s wire’ is similarly soft and workable, if thinner wire is needed.

Metal mesh

Various sizes can be found, ranging from fine ‘impression mesh’ (usually copper or aluminium), which is punched, to larger-scale welded wire mesh. Impression mesh can be moulded to an extent because the holes will expand or contract. The finer varieties can be used for creating rigid curtains, while the larger are commonly used as bases for terrain modelling. Welded wire mesh is not mouldable in the same way, but has other special uses which are illustrated in Chapter 4.

Wood

It is becoming less common for either the freelance or the occasional model-maker to use wood as a constructional material, despite its heritage, because it demands more of an equipped workshop set-up. Also, good-quality, thin sheet wood is generally more expensive than the alternatives, or is harder to obtain. An exception might be made sometimes in the case of architectural models, where a clean wood surface may be valued for its aesthetic qualities. But even here it is common to construct first in plastic and apply the wood as a finishing layer. The other exception is where a firm, solid material is needed as a baseboard. More about woods such as obeche, balsa and walnut has been included in the section of the Directory dealing with surfaces.

MDF

This is a processed form of wood composed of tightly pressed fibres bound together with glue. The initials stand for ‘medium density fibreboard’. It is easily obtainable from builders’ or timber merchants, or DIY centres. Good model shops may stock thinner types down to 2mm. It has its advantages as a cheap constructional material which can be easily glued using PVA wood glue. It is commonly used for baseboards because it maintains its flatness better than plywood, but these can get very heavy.

Wood strip and dowel

Model shops will stock a wide variety of strips and dowels (round section) in various thicknesses while DIY centres will offer larger sizes. The light-coloured woods in model shops will tend to be bass, obeche, spruce or pine, while the harder, darker wood is usually walnut. DIY centres will often stock strip and dowel in pine or ramin. Ramin is slightly harder and denser and maintains its straightness better.

Card

Mountboard

This is a relatively soft, fine display board obtainable from art and graphics shops or picture framers. An A1 sheet will average £3. It is a good constructional material for medium-size forms and the black version is useful for model boxes. Although there are cheaper versions available, the type commonly stocked is the Studland brand from Daler-Rowney. This comes in a standard A1 (594 × 841mm) size, is 1.4mm thick (or 1,400microns as it’s usually measured) and consists of one side covered with a coloured paper, while the other side is left white. The choice of colours tends towards pastel because the card is designed to be cut into frames, or passepartouts,when mounting drawings or prints under glass. The coloured surface is also usually matt and very sensitive to marking. Thinner mountboard, for example 1,000 microns, is also available, but usually only from specialized paper shops.

The Daler version is easy to cut smoothly, although some cheaper versions tend to be harder. It is not suitable for slender or intricate forms, partly because of its thickness in scale (1.4mm makes 35mm at 1:25 scale, which is not bad for a chair leg but too chunky for a window frame), but also because it is too fragile at that size. It will also tend to separate into layers when you try to cut a strip any thinner than about 3mm wide. It will not bend readily and if curved shapes are needed the card has to be scored in repeated lines to assist it (see Chapter 2).

Stencil paper

This is a strong, oiled paper suitable for cutting intricate forms, also known as oiled manila. It can be found in most art shops or specialist paper shops and averages £3 for an A1 sheet. Because of its natural, wood-like colour it is a good surfacing material for wood effects. It is more a thin card than a paper (300microns or 0.3mm thick). The linseed oil serves two purposes. Firstly, it stops the paper from absorbing water while stencilling, which lengthens the working life of the stencil. Secondly, it gives the paper a smoother composition, which enables quite intricate cutting and eases the friction on the scalpel blade (similar to cutting through wax). Despite this, the card is surprisingly rigid for its thickness. It is ideal for cutting window frames or for building up moulding profiles where mountboard would be too thick.

Foamboard

Foamboard is a very light, thick, stable board which consists of foamed polystyrene sandwiched between tough paper layers. It is found in any art or graphics shop. An A1 sheet of 5mm foamboard will vary between £4–£6 (it is usually also sold in 3.5mm and 10mm thicknesses). It can be used for building quick and sturdy sketch models and for white-card models in film and architecture. It is also used for building theatre model-boxes or as a mount for soldering templates.

Depending upon where it comes from, it is known variously as foamcore, featherboard or polyboard. White is most often used, but it also comes in black. No colours are produced as yet. It can be glued (surface to surface, or edge to surface) with PVA (preferably the Loctite, Weldbond or Evo-Stick ‘fast-grip’ variety), so there is usually no need to use a special foam glue. Edge-to-edge gluing will not be very strong, whatever one uses. Avoid UHU as this will dissolve the foam interior on most brands and spray paints will do the same. It should not be confused with Kapa-line foamboard when attempting to use it as a sculptural or textural material. The paper covering cannot be removed easily and the foam itself is very fragile.

Kapa-line foamboard

This is a superior type of foamboard with a polyurethane (rather than polystyrene) foam centre that can be found in art shops and model shops. It is more expensive than standard foamboard, on average £8 for a 30 × 40in (76cm × 102cm) sheet. Apart from being used as a normal foamboard for all of the above, the interior foam can be used for a variety of sculptural or textural effects. Many years ago this seemed to be the type of foamboard most available, but then cheaper brands flooded the market. What is special about Kapa-line, and what sometimes justifies the higher price, is that the paper layer can be carefully peeled off. The foam inside can be carved, sanded and will take impressions particularly well. It will also glue more readily with PVA than the standard polystyrene versions and solvent-based glues such as UHU do not dissolve it.

Materials for mould-making and casting

Mould-making

Silicone rubber

This is the best choice when a flexible mould is needed and fine detail has to be faithfully reproduced. Silicone rubbers are the most widely used professionally. They come in many varieties, with different degrees of hardness, setting times and methods of application. They are fairly expensive (averaging at £25 per litre) and their shelf-life (the amount of time they keep after buying them) may be limited to six to twelve months.

The Shore A number denotes hardness when cured, or set. For example, the type featured in Chapter 3 (RTV-101 from Tiranti) is relatively hard at Shore A 55. Often these harder silicones will also be heat-resistant. (RTV-101 can be heated up to 260°C, for example, which means that it is suitable for making castings in low-melt metals, plus a polymer clay such as Super Sculpey can be press-moulded into it and baked in a domestic oven.) Most silicones can be poured and come in two parts, comprising the rubber itself and a liquid catalyst. These have to be properly mixed for the rubber to cure. Directions are usually clear and straightforward as to how many drops of catalyst are needed per 100g of rubber (the usual by weight is around 5 per cent of catalyst to rubber, but dropper bottles make dosing a lot easier). There is often a comfortable margin for error! A calibrated beaker is necessary for measuring out the rubber and this (together with any mixing sticks used) should be as clean as possible because most substances which harden by chemical reaction are sensitive to contamination. This may result in the silicone not curing properly, or needing a longer time to do it.

Depending upon the type, silicones need anything from a couple of hours to a few days to cure normally. Adding less than the average recommended amount of catalyst may lengthen the working time but also the curing time. Adding more will have the opposite effect. Most pouring silicones can be altered by the addition of a special thickening agent which turns them into a spreadable gel. This means that they can be brushed onto the surface of a prototype as a thick layer (rather than cast as a block), saving on the amount of silicone used. On its own, this thick skin would be too flexible to make casts from, so it needs to be held in place by a separate ‘jacket’ of plaster cast over the top. The thickening agent will tend to cause the mixture to start setting more quickly, so speed is crucial when using this method.

Although silicones can’t be re-melted in the way that vinyl can, one useful economy can be made with moulds no longer needed. They can be chopped into little pieces and used to ‘pack’ new moulds in the making. As long as the rubber is like-for-like, and as long as the prototype is first coated with some of the fresh mix, the rest of the mould can be largely recycled filling, bound together with more of the fresh mix. It is possible to save considerably on the amount of new rubber one has to use in this way. As long as there are no air gaps, there will be little difference in the mould’s elasticity or strength.

On the whole, one needn’t worry about trapped air bubbles when using either silicone or polyurethane rubbers. The curing time is so long that any trapped air, being much lighter than the rubber, will work its way to the surface long before the rubber starts to harden.

Polyurethane rubber

Polyurethane rubbers have very similar properties to silicones, but the main difference is that most are supplied and mixed in two equal parts (parts ‘A’ and ‘B’). Some are tougher than silicones and better suited to casting in abrasive materials such as concrete. Like silicones, they also come in a range of hardnesses and other properties. Whereas silicones are unaffected by a wide range of prototyping and casting materials, and often no special barrier or release agent is required (although a thin coat of vaseline always helps), the same is not true for polyurethanes. You must fully acquaint yourself with the technical data and recommendations supplied with the product. Often special sealing or release agents are recommended and this should be taken seriously, otherwise you may end up with a mould that’s completely stuck to the prototype, or a mould full of rubber that refuses to set (because the polyurethane has reacted to something on the prototype which inhibits the curing process). Certainly, you can’t use polyurethane rubber to make a mould and then cast polyurethane resin into that mould without the proper release agent – they will stick inseparably to each other without it. That’s why, on the whole, it’s better to use silicone rubbers as much as possible just in case you decide later to try castings in polyurethane resin.

Gelflex

This is the brand name for one type of re-meltable vinyl, another being Vinamold. Both are available in either ‘hard’ or ‘soft’, although even the hard versions are relatively soft compared to some silicones. Gelflex is supplied in blocks and needs to be melted at around 140°C before it will become liquid enough to pour over a prototype. This means that only heat-resistant prototypes are suitable, but polymer clay, wood or plaster will serve the purpose. When it has set, Gelflex forms a flexible mould similar to rubber, but not nearly as durable. There is a limit to the number of ‘pulls’ (castings) that can be made from a vinyl mould before the surface deteriorates or the mould itself starts to tear. In addition, Gelflex is unsuitable for reproducing fine detail because it starts thickening immediately on contact with the cold prototype and deeper detail may therefore be lost.

The main advantages of using this type of vinyl are speed and cost. The mould is ready to be used as soon as it is cool, which could be under an hour for a small form (a larger block of Gelflex may need a good few hours to cool and set; it’s best to wait as long as possible because even though the surface might feel firm and cooled, the centre could still be soft). The main advantage is that it is much cheaper than silicone by weight (averaging £6 a kilo), but old moulds can also be re-melted more than a few times. This makes it the best choice for making simple castings on a low budget.

Although expensive heating units are available, Gelflex can be melted in an ordinary saucepan on a low heat (a milk saucepan with a pouring lip is useful). If this is done, however, precautions are very important! Ventilation must be good because fumes are given off in the process and the melting Gelflex must be constantly watched and stirred. It will turn a greenish colour if it overheats. This will produce more fumes and will also shorten the life of the Gelflex for future use.

Gelflex will accept both polyurethane resin and plaster without the need for a release agent. Another useful advantage of Gelflex is that, because of its low melting point, the inside surface of the mould can be smoothed using a heat gun. This can sometimes do a better job of removing surface imperfections than sanding the prototype, although this technique requires a lot of practice and experiment to get the level of heat, distance and duration right.

Latex

Liquid latex sets by evaporation of the water within it, so it is ready to be used without any mixing of parts. However, because of this evaporation it shrinks noticeably as it dries –anything up to 10 per cent. This, and the fact that it can only be built up in layers, make it unsuitable for any serious or detailed mould-making. A ‘sock’ or ‘glove’ mould could be made by building up layers on a very simple shape (preferably of plaster), peeling it off when dry and casting plaster into it. This might need anything from four to ten separate coats to make a mould with any strength. A thicker collar of latex should be included at the base of the mould to stop it from collapsing and to hang it from when pouring the plaster. There will inevitably be some distortion of the form.

Plaster

Plaster is more often used in model-making as a casting than a mould-making material because of its inflexibility. One exception might be when a slightly flexible material such as Super Sculpey is press-moulded into a plaster mould, as described in Chapter 3. Another occasional exception might be the technique known as ‘waste moulding’, which is suitable for making just one copy of a form where undercutting is not a particular issue. The form to be copied is first covered with a thick shell of one of the softer plasters, usually in a few layers. As long as the prototype can be extracted from the plaster shell there may be no need to make this in two parts. A hollow plaster receptacle remains, and if one then fills this with a much harder plaster the softer plaster can be carefully chipped away from it once set, hence the ‘waste’ part. The mould is also destroyed in the process. A good barrier such as mould-maker’s soap or vaseline is needed on the inside of the mould.

It is common for the shell to be built up with a relatively thin layer of plaster first to get into the details (often by a technique of ‘flicking’ wet plaster onto the surface with the hand). This is then followed by a layer of plaster-soaked fabric such as jute scrim. This serves to strengthen the shell, but it doesn’t need to be particularly thick (performing the same function as glass-fibre matting in resin lamination). This also helps when chipping the shell away at the end because it will detach itself in larger pieces.

Casting

Polyurethane resin

Like its rubber counterpart, polyurethane resin comes in two equal parts for easier mixing. It is available in both clear and opaque versions and special colourings can also be added to the mix. The type featured in Chapter 3 (DRO 29, discontinued in 2009) starts as two clear liquids which become an opaque ivory when set. This happens rapidly, the pot life (the amount of time it stays pourable after mixing) being only a matter of minutes. Cast elements can be removed from the mould in as little as fifteen minutes. They will not yet be set totally hard, but will be hard enough to detach from the mould; full setting may take a few days. This ‘green’ (still soft and flexible) stage is useful for trimming the forms. A resin of this type is essential for any casting of detailed or slender forms. Even a fine, hard casting plaster would be too fragile. Polyurethane resin accepts acrylic or enamel paint well, though a much better painting surface is obtained by spraying with Simoniz car primer first.

Polyester resin

This is the material normally used in conjunction with glass-fibre matting to produce fibreglass. What results is a very hard shell, which, depending upon the number of applied layers, is extremely rigid and weight-supporting. The most common use in the ‘real’ world is for boat-building, where a durable but light shell is needed for the hull. In theatre and film, it serves to reinforce landscaped areas, making them fit to walk on. But there is usually little justification for going to this trouble in a model of average size, where load-bearing strength is usually not an issue and where there are other, simpler ways of constructing a shell with adequate strength.

Polyester resin is also normally used for clear castings, that is, as a means of embedding an object in clear plastic. For this purpose special clear-casting resins have been developed, as opposed to the more general-purpose type for fibreglass lamination. As a material, it is so fraught with complication that there is, again, little point in using it unless it’s definitely the only option! The only other advantage to it is that many polyesters have a relatively lengthy curing time, which means that they have a long pot life and so can be used (with the addition of fillers and pigments to create opacity) as a tough gap-filling lacquer to build up a smooth shell on a form. Most other resins would start to set too quickly for this.

Polyester resin hardens with the addition of a catalyst and here the most exact measurements are crucial, because if too much catalyst is added the chemical reaction produces a lot of heat, which can cause the whole thing to crack. There may be this danger anyway because the chemical reaction produces more heat the more plastic is mixed, so a large block could harbour awesome temperatures at its core. The percentage of catalyst recommended is small, so there is less room for error. Many other factors can affect the curing, such as temperature and humidity, but especially the mould material, or, in the case of clear casting, whatever you’re pouring it on top of. It is best to read the manufacturer’s recommendations for treatment of these surfaces prior to using it.

Plaster

Most of the plasters found in DIY centres for small building jobs are usually too coarse, soft or slow-setting to serve any purpose here. The plaster labelled as ‘plaster of Paris’ is not necessarily a special type (the phrase just means ‘plaster’ or gypsum and originates from the fact that there was a large gypsum deposit outside Paris). If you find this either in a DIY centre, chemist or hobby shop, there is no guarantee that it will be fine or strong enough for small castings and it should be tested first. The surest choice is a proper casting plaster such as Basic Alpha or Crystacal, from a sculptor’s suppliers such as Tiranti. Basic Alpha (featured in Chapter 3) is very fine, quick-setting and hard. Directions for mixing it (the plaster is always added to the water) are given in the chapter. Some sculptors prefer to mix it exactly according to the optimum plaster/water ratio. In the case of Basic Alpha this is 2.8k/ltr. There are even harder plasters, usually requiring a higher proportion of plaster to water.

Basic Alpha can be made even stronger by mixing it with a special plaster polymer (an acrylic resin) in place of water. Plaster and resin need to be mixed faithfully (three parts plaster to one part polymer), rather than the usual ‘by eye’ method. For large amounts power-assisted mixing is recommended, but small amounts can easily be mixed by hand as long as this is vigorous. What results is a creamy mixture that will set exceptionally hard and is much less brittle than the water-mixed plaster. It can even be used, with appropriate matting, as an alternative to laminating resin without the harmful vapours. It is a little too thick to flow in the way that the polyurethane resin will, but is perfect for larger forms, also working out cheaper at about £8 per litre.

Polymer clay

The technique of casting using a clay substance is not very common because it is unlikely that any normal clay will set in a mould and in any case there’s the question of how to get the clay in there in the first place. Clay is, of course, commonly used for casting pottery, but in its liquid form, slip. The emergence of polymer clays that can be fired hard at relatively low temperatures, combined with the development of silicone rubbers that can withstand these same oven temperatures, have really opened up the possibilities of using this method.

The easiest technique is to press-mould Super Sculpey into a flat one-piece mould as demonstrated in Chapter 3. The resultant ‘pull’ can either be laid unaltered on a ceramic tile or baking tray in the oven, or the shape can be modified (the Sculpey leaf shapes, for example). This method makes it possible to create a large number of casts, or variations, in a short time.

But Sculpey can also be cast in a two-piece mould with a bit of extra care. This involves pressing softened Sculpey into the two halves of the mould separately, just proud of the dividing edges. The two mould halves are then pressed together (in a kind of turning/rocking motion to join the clay together – this needs to be practised!). The excess clay should be squeezed out along the seam line and should be trimmed off when baked. The whole set-up goes in the oven, for a little longer than the time recommended on the polymer clay packet. Of course, this is only possible with the appropriate mould rubber, such as RTV-101.

Latex

In the context of casting materials, latex has just one use, but a significant one. The practice of making latex skin, or surface, casts is quite common in model-making and was used extensively in film until silicone started replacing latex. It involves making a flat 3-D negative of a surface feature or pronounced texture, onto which latex is then painted in a number of layers. When completely dry, the latex can be peeled away, having formed a positive copy. This skin can then be glued onto a flat surface or wrapped and stretched around one that’s not flat. One can therefore generate an unlimited supply of a particular surface effect for a wide variety of applications.

It’s not worth trying to brush latex into a mould, as the brush will become unusable very quickly, however careful you are about rinsing it between applications. A better and quicker method is to pour more latex than you need directly into the mould, rock it around until the whole surface is covered, then pour the excess back into the pot. If you stop once the dripping finishes you’ll know that there’s neither too much nor too little latex for the layer. It can take anything from thirty minutes to an hour to dry, depending upon the material of the mould. If it is plaster, the process is quite speedy because the plaster will absorb water from the latex mixture, but if it is sealed styrofoam or plastic the drying time will be quite a bit longer.

Special latex colours are available to add to the mix if you want a base colouring to the skin. This is always a good idea because you can judge the resultant texture much better. Only a very minimal amount of colouring is needed because the latex itself is semi-transparent. Most concentrated toners for emulsion paint (available from decorating stores) will work just as well.

Successful painting of latex is more of a problem, however. Straight acrylic might adhere to the surface at first, but will crack and peel off in time because it is not being allowed to key properly. There are other methods, such as mixing some acrylic with latex to form a paint, but this is not guaranteed to work. What does adhere to latex very well is enamel paint. It will tend to react with the latex surface, however, and so its drying time will be longer than usual, although it will not be unreasonable. The enamel paint will also stretch with the latex to an extent without flaking.

Modelling materials

Super Sculpey

The particular type featured in this book is Super Sculpey, which is flesh-coloured and available in 1lb boxes. The price averages £9 a box, making it more economical than others in the Sculpey range. It is a polymer ‘clay’, in fact largely a type of plastic, and needs to be heated up before it will harden (FIMO is another similar material). Although the manufacturers recommend baking it in a domestic oven (130°C is sufficient), it can be hardened just as easily and more quickly under a heat gun on medium setting (full details on working with it are included in Chapter 5).

The supreme virtue of Sculpey is that it possesses even more softness and ‘plasticity’ (when worked a little between the fingers) than plasticine without any of the stickiness. Some synthetic modelling materials have a certain tough elasticity, meaning that when one tries to make a slight impression they will resist a bit, which makes modelling with them frustrating. This doesn’t happen with Super Sculpey. Its other virtue is that an unfinished form can be hardened, either totally or partially, to form a more stable base for further modelling. Fresh Sculpey will stick to hardened material without any problem and there is seemingly no limit to the number of times the same piece can be subjected to heat as long as the level of heat remains under that recommended.

Milliput

This is an epoxy putty which consists of two parts that have to be mixed together thoroughly in equal amounts. When mixed, it has roughly the same consistency as plasticine or Sculpey, but will begin to harden (depending upon room temperature) after about forty minutes. Within just a few hours it will become rock hard, but this can be accelerated to minutes if heated. It is partially soluble in water until it hardens, so water can be used to soften and smooth the surface. However, because of this it also softens with moisture from the fingers and so the fingertips do tend to get ‘gunged up’ quite quickly, which can make detailed modelling difficult. It will also stick too much to modelling tools. There are five different types available, white being the finest and more expensive at around £6 for a 4oz pack. Standard Milliput is yellow-grey, coarser and cheaper. Black and terracotta are the other colours available. When Milliput is more thoroughly ‘cut’ with water it can be used as a gap-filling adhesive, a soft filler, or even as a relief paint.

Plasticine

The most available type of plasticine is Newplast, made by Lewis, in 500g packets (averaging £1) with a range of colours. Most people will be familiar with this material and guess that it is only suitable for temporary work because it never hardens. It is very malleable, but too soft for professional modelling. It tends to melt on the fingers, making fine work difficult. Putting work in the fridge for a while will help a little, but only temporarily. A little more durability can be given to plasticine by coating it (perhaps two to three times) with PVA. This will give it a slightly tougher skin which can then be painted. Forms created this way will last but they still have to be handled with care, because the soft plasticine is merely contained within a thin flexible skin. It can be used as a filler in emergencies if sufficiently coated in this way. It is more useful for modelling prototypes from which moulds can be made, especially in plaster because it is water-repellent.

Chavant clays

These professional oil-based clays have a similar composition to plasticine, but are available in three degrees of hardness and two standard colours (grey-green and terracotta). Apart from being easier to work with, they are non-sulphurated, meaning that they are more compatible with silicone rubber when making moulds. Chavant clays are industry standard, along with Sculpey, for the creation of character maquettes, but the harder variety is also suitable for modelling precise streamline forms such as car models because it can be worked to an immaculate finish.

‘Green stuff’

This is an affectionate name, widely used, for a product similar to Milliput. Its actual name is Kneadatite. Like Milliput, it comes in two equal parts which have to be kneaded together (in this case, a strong yellow and blue component, from whence arrives the ‘green’ of its stage name). Its advantages over Milliput include that it accepts even finer detail and has a longer working life before it starts hardening (one and a half to two and a half hours according to room temperature – the lower the temperature, the longer the time). Full hardening will take about twenty-four hours.

Like Milliput, it’s partially soluble in water, a property that can be used for smoothing or cleaning. It is supplied with the yellow and blue strips already stuck to each other. This may assist in measuring out equal amounts, but it also means that where these touch the material will have begun to harden. The manufacturers recommend cutting this middle strip away, so already there has been a bit of wastage! This may not matter except for the fact that Kneadatite is expensive compared to the alternatives. When mixed, it is extremely sticky (even on metal), which is an advantage when working with armatures but causes problems when trying to model. Even fans of the material have likened it to trying to sculpt with bubblegum! Lastly, although it accepts paint well, green is hardly a natural colour to want to model with.

Air-drying clays

These have long been considered something only for children, because originally this type of clay was a form of pulped paper and as such had a coarse, uneven consistency. The material was also prone to heavy shrinkage and cracking. Now there are many different types available. Many are still fibrous and so not suitable for fine detail, and anything which dries by evaporation will inevitably shrink. But they are cheap, on the whole, and can be used as a basis form as long as they’re given enough time to dry thoroughly.

Materials for creating surfaces

Texturing materials

Polyfilla

Originally a specific brand name, the word has now become a blanket term to describe a wide variety of water-based fillers for repairing wall surfaces and other home decorating jobs. These fillers dry by evaporation and are invariably white. Although some still come in powder form, most are now sold ready-mixed. Properties vary quite significantly according to the brand, including how well they stick to surfaces, how much they shrink and how hard they dry. On the whole, the most effective ones for model-making purposes are the so-called ‘fine surface’ fillers because these can be spread more thinly and will achieve more detail. The particular brand recommended here is the fine surface version made by the original Polyfilla firm, Polycell. This is more akin to an acrylic paste and will stick to almost anything, however thinly applied. Shrinkage is minimal and it dries tough but also remains quite flexible. This makes it ideal for giving a slightly more durable surface to styrofoam, for example, where other plastic fillers would dissolve the surface. For more about texturing with it see Chapter 6. If mixed with water to an even, creamy consistency it can be used as a relief paint and this is described in Chapter 5. Alternatively, inert substances such as sand, granulated cork, ground olive stones or fine gravel can be added to create even more textural possibilities.

Similar products worth noting here are Idenden Brushcoat or Rosco Foamcoat, both made specifically for scenic texturing and widely used in theatre and film. They are even stickier and more flexible when dry. They could be useful to the model-maker if they were available in smaller amounts, the smallest for Idenden being 10kg, for example. On the other side of the scale, there are whole systems of texturing or impasto pastes, some with gritty additives, to supplement acrylic paints and available from art shops. These tend to be overpriced for the amount one gets and the polyfilla cited above will generally do just as good a job at a fraction of the cost.

Two-part fillers

These usually consist of either an epoxy or polyester resin with some inert filling substance already mixed in and come either in two equal parts or a bulk part and a catalyst. These need to be thoroughly mixed together for the filler to harden. The main advantage over water-based fillers is that they set by chemical reaction rather than evaporation so they will not shrink. They can therefore fill much bigger gaps or be applied more thickly. For model-making purposes another advantage is that they are unlikely to warp the surface they’re applied to. But they are expensive and their fumes can pose a health hazard. Car body fillers of this type can usually be found where car maintenance products are sold.

Cladding Materials

Obeche wood

This is a very popular wood with model-makers, being relatively soft, pliable and easy to cut while being harder and more resilient than balsa. It comes in sheets down to 0.8mm thick, as well as a range of rods and strips. Although common in model shops it is rare to find it anywhere else. It is light in colour, of a medium density and accepts stain very well. The grain is not obtrusive, although certain structures appear when staining so tests need to be made first.

Balsa wood

This is perhaps one of the most familiar model-making materials for ‘early years’ and certainly a cheap one, but is not so widely used professionally because it is so fragile. It can be useful as a surfacing material though, especially where the effect of rough, weathered beams is needed, because balsa can be easily broken down with a wire-brush along the grain. It will take paint and glue well, but staining often appears washed out with a silvery sheen. It can usually be found in blocks, strips or sheets down to about 1mm.

Walnut, bass and spruce

These are the other woods most commonly available in model shops. Walnut has a darker colour and is more brittle and harder to cut than obeche. Bass is very light in colour and relatively soft, without much of a noticeable grain. This can be a better choice for cutting intricate or curved shapes. Spruce has a very prominent grain emphasized by resinous lines. This may be good sometimes for floorboards but it also makes spruce harder to cut evenly with the scalpel.

Cork sheet

This can make an interesting surface texture and is surprisingly durable. It will accept paint well and can be mounted either with Spray Mount, PVA or contact adhesive. There is a range of grades and thicknesses, the thinnest being about a millimetre. Thicker sheets can be broken down a little using a wire brush or knife point.

Kapa-line foamboard

Unlike the standard, cheaper foamboard, the surfacing paper on Kapa can be peeled away. What remains is an even sheet of very impressionable polyurethane foam which can be scored, carved, sanded or imprinted. The foam is not ‘springy’, staying put when pressed, and will not expand when painted. It will accept even thin washes of paint very well and its ivory colour makes a good base. Polyurethane is resistant to most solvents, so, unlike styrofoam, it can be sprayed with even acetone-based paints and will accept most glues. It is available in thicknesses of 3mm, 5mm or 10mm.

Styrofoam

Although mainly useful as a building material, and more commonly available in thick sheets or blocks, thinner sheets (down to 1mm) can be found in more specialist model shops. These can be scored or embossed in much the same way as Kapa, though not quite as well because of a slight skin on the surface. Styrofoam will dissolve in solvents such as acetone, which limits the choice of glues and paints. Its fine-celled structure is very easy to cut, carve or sand to a smooth finish. Different densities are available.

Foamed PVC

For more about this material, see ‘Materials for Construction’ or Chapter 2. In itself, foamed PVC sheet has no interesting surface texture, but being relatively soft it can be scraped with coarse sandpaper to give it a fake grain which can suggest wood reasonably well when painted. Lines can also be easily embossed using a hard point.

Latex

The technique of using liquid latex to create textural skins is described in Chapter 3. Latex is available from sculpture suppliers and some art or hobby shops. It averages at around £8 per litre. Moulds for casting the skins can be made from either Kapa-line foam or plaster. Although the former are quicker to make, latex will dry more rapidly on plaster and detach itself more easily. Two coats are usually needed to form a strong layer, the first left to dry properly before the second is added.

Vinyl wallpapers

These are composed of a soft paper layer onto which a foamed plastic pattern is printed. There are countless organic, floral or geometric patterns to choose from and DIY centres will often have opened rolls on the shelves from which to take samples. They will take paint well, though the vinyl pattern will tend to resist a very thin wash. This can, however, be used to good effect to accentuate the pattern.

Decorative papers

A visit to a specialist paper shop such as Paperchase will present many other options for using ready-made surfaces. Patterned writing paper may provide just the right marble effect, or there are other, larger sheets with a variety of embossed patterns. Many hobby shops now have a whole section devoted to card and scrapbook decoration and this has also become a good source of unusual paper surfaces.

Sandpaper

Abrasive papers come in a variety of grades and can offer a cleaner, quicker alternative for creating surfaces such as asphalt or pebbledash. It is sometimes difficult to imagine how the surface will read when painted, so it is a good idea to build up a collection of painted samples. Also, the effect produced can be too uniform to be realistic and may need to be enhanced by gluing extra sand in places.

Oil-painting paper

This is supplied as an alternative to canvas and has a fine canvas imprint. It has already been treated with a layer of primer suitable for oil- or spirit-based paints, but will accept other paints if they are not too thin. The slight texture can give a flat colour a little more vibrancy even if no obvious texture is needed in the model. It is worth considering spray-mounting it onto PVC or card for a more versatile painting surface. It can also suggest worn, woven carpet especially as thin paints can be rubbed away, exposing the texture more.

Stencil paper

As evidenced in Chapter 6, stencil paper has a sympathetic wood-like surface which can be further enhanced by staining. Although the paper has been impregnated with linseed oil to make it tougher, it will accept water-based paints and PVA to some extent. It is available from most art or graphics suppliers.

Velour

The term ‘velour’ is often used to denote the adhesive plastic material found in hobby or decorating centres, or various types of flocked paper. These are useful for representing black masking curtains in a theatre set model, small-scale grass or carpets. An appropriately thin paint or ink needs to be used if the surface requires painting.

Scatter Materials

Granulated cork

This is sold specifically in model shops for creating scenic effects and usually comes in three different grades: coarse, medium and fine. It is cheap, light and takes glue and paint very well. It can even be dyed, although its natural brown colour limits the range. It is ideal for changing the consistency of polyfilla without adding to the weight, for example in achieving convincing earth effects.

Sand and grit

Sand is an obvious choice for fixing with glue to create a texture or adding to a polyfilla mix, but may not be so easy to get hold of in small amounts. The best option is to collect a little as and when you next see it. Model shops may stock a variety of scenic sands and grits down to a very fine grade, otherwise pet shops are a good source for sand, as well as for different types of gravel or fine stones for aquariums. If rather pushed in terms of time, the kitchen can offer some solutions – sugar can be used instead of sand or instant coffee instead of grit, for example. Both can be sprinkled into PVA without loosing too much of their structure. They need to be properly sealed, however, preferably with a spirit-based paint, otherwise they are unlikely to last.

Vermiculite

This is a naturally occurring mineral which expands when heated. It is sold in granulated form as an insulation material in building and can also be found in garden centres as a soil filler. It is popular with scenic workshops for creating a heavily textured paint because it is light and inert, that is, it will not affect the properties of the paint. As it comes, it can make convincing stones for scenic models, but can easily be broken down further for other effects.

Sawdust

One advantage of sawdust is that it can be dyed, stained or glued so well. Model shops usually sell a range of greens and browns for scenic effects, otherwise different grades of sawdust can be found in pet shops.

Poppy seeds

Found in the supermarket (usually in the baking section), poppy seeds are quite effective for representing pebbles at a small scale. Also, because they are quite regular in size and shape, they suggest small leaves such as privet very well, as illustrated at the end of Chapter 6.

Sisal

Chapter 6 describes a method for creating a grass effect using clumps of dyed sisal pulled from the special mats for lining hanging flower baskets. Garden centres are therefore the best source for this material. Sisal is a natural fibre used in rope-making and carpeting.

Eggshell

Most scatter materials are granular, but at times a material more like flakes or plates might be needed to create a certain effect. A case in point is provided by the technique for suggesting leaves in Chapter 4. Eggshells can be easily crushed to form leaf-like particles; if a proper mortar and pestle is used the size can be controlled.

Tea

The tea powder from used teabags makes a very good soil, either scattered into glue or mixed into a paste with PVA or paint.

Painting, staining, dyeing and finishing materials

Painting

Primer

Primer is a special, cheaper paint for sealing absorbent surfaces prior to painting. It may not be necessary in all cases, but is advisable. It also helps to prevent warping if a non-water-based primer is used. Primer will provide a better key for painting on plastics or metals and is available either in brushable or spray form.

Acrylic paint

Acrylic is a water-based paint, most familiar from art suppliers in tube form, although nowadays many household paints also have an acrylic base. A better range of colour is achievable with acrylic than perhaps with any other paint except oil. It is one of the most versatile forms of paint. However, it is designed for comparatively rapid use and hardly has one mixed up a colour on the palette before it starts to dry out! Tube acrylic needs quite a bit of encouragement before it thins properly with water and the results are often unsatisfactory. If used straight from the tube it clogs detail, deposits visible brush strokes and leaves an undesirable silky finish which is neither one thing nor the other … and usually totally unsuitable considering most natural or natural-looking surfaces tend to be matt!

An exception might be the more liquid acrylic mixes designed for airbrush work and available in plastic bottles (for example, DecoArt’s Americana or the range from Inscribe). These will not dry so quickly, coverage is better and thinner, and they generally dry more matt.

Gouache

Gouache is quite simply watercolour paint which has been made more opaque with the addition of fillers. It can be very versatile, can be thinned down more easily and is relatively inexpensive. If it dries, it can be dissolved again with water, but this makes it unsuitable for overpainting, or building up ‘glazes’ of paint because a second application will immediately mix with the one underneath it. If used as it comes, it needs to be spray-fixed or brushed with a spirit-based sealant or varnish if you want to preserve it, especially on objects which are going to be handled such as model figures. A better alternative would be to mix an equal amount of PVA glue with it to make it self-sealing. This will also help it to adhere to non-porous surfaces such as plastic.

Enamel paint

This is a fast-drying, oil-based paint available in small tins that has been developed specifically for painting on plastic. It will therefore usually adhere to anything, covers exceptionally well without streaking, dries matt (if matt versions are chosen) and will keep in the tin for a long time. Being oil- rather than water-based it will not warp any surface, even thin paper, but unlike standard artists’ oil paint it will harden properly on paper or card. Satin and gloss versions are also available, with most being very opaque. The main producers are Humbrol or Revell.

One drawback is that the choice of colours tends to concentrate on the muted rather than rich primaries, specific to military model kits. Another is the vapour produced by the solvents. Good ventilation is essential when using them, especially because white spirit needs to be used to thin them or clean brushes. Tins cost around £1.20 in the shops (although they can be cheaper on the Internet) and they can be found in all good model shops and some artists’ or hobby shops.

Colourings or ‘toners’

These are concentrated paints intended for changing the colour of other paints or materials, for example wall emulsion paint. They are usually available from more specialist decorators’ shops. Some colourings are designed to mix with a variety of media including casting resin or latex. They are particularly useful for making a coloured basecoat from standard white emulsion, or changing the colour of polyfilla.

Aerosol paint

Many of the spray paints one sees (for example, the Simoniz brand car body primers available in matt white, mid-grey or brick red, the glossy car colours in garages, or the household spray colours in DIY shops) are cellulose-based and the solvent in them is acetone. This is why they will dissolve the surface of styrofoam and some other plastics; it is also why acetone will clean or dissolve them. They’re not very economical to use for overall coverage (for example, to turn a white model box black!) and will release headache-inducing vapours into the air when used in this way. But they’re perfect to have on hand (even if it’s just matt black, grey or rust) for slightly modifying painted surfaces, such as to tone down, to darken and so on. If surfaces to be sprayed are sprinkled liberally with sand or sugar before spraying a very satisfying mottled or fragmented effect can be achieved, especially if repeated with more than one colour. Otherwise using a spray paint has advantages if you want to achieve a very flat, even surface without brush marks.

French enamel varnish

Usually referred to as FEV for short, this comes in a number of transparent colours. It has natural shellac as a base. FEV is fairly fast drying and can be used as a coloured glaze on glass and plastic. It is also useful for staining and varnishing wood at the same time.

Staining and dyeing

Wood stain

There are many available, either water-based or spirit-based, their colours corresponding to the types of wood intended. Spirit-based stains tend to infiltrate better and will not warp the base material. They are expensive, though, if it is necessary to experiment with different colours; mixture of white spirit and pigment (from pastels, shoe polish and so on) generally works just as well.

Liquid shoe polish

These work quite well on wood or cardboard to create a polished wood colour, getting progressively richer and shinier with each coat. They are usually water-based, which may lead to warping.

Inks

Apart from a range of bottled inks available from art materials shops, the leftover ink from inkjet cartridges makes strong and vibrant colours. This can be thinned with water, but it needs to be sealed or a little binder such as PVA can be added. The results are not fade-proof, however.

Dylon dye

This dye powder can also be mixed with white spirit or with hot water to make quite a powerful stain. Otherwise it can be used as intended for dyeing materials in a hot bath (such as a saucepan on the stove) with the addition of salt. Scatter materials such as granulated cork or sawdust can be customized in this way. Rice or shredded coconut can be given very strong colours, even rich black, to provide other interesting alternatives.

Finishing

PVA

If only a sealant is required to protect a fragile or powdery surface, heavily diluted PVA may be sufficient. There will be a slight change on a matt paint surface. Increasing the amount of PVA will make a good satin varnish and successive coats will increase the shine.

Polish

Often spraying a painted surface with a little furniture polish, leaving for a while and then buffing with a rag, will produce a satisfying result. The advantage here over liquid varnishes is that the inside corners remain a little matt rather than glossy, which improves the overall effect. Straight varnish will tend to look too glossy and will highlight every imperfection.

Special effects

Glass frosting

Available only as a spray, glass frosting will produce a translucent frosted effect on glass or acetate. A quick, light spray will produce a light frosting that can be intensified with further coats.

Metalcote

Made by Humbrol, this type of enamel needs preferably to be painted on a hard smooth surface. The paint must be left to dry thoroughly, then it can be buffed with a rag to produce a convincing metallic finish. It is available for various metal effects ranging from aluminium to gunmetal.

Finger Gold

A suspension of metallic particles in a waxy base, which, as the name implies, can be rubbed on with the finger. When buffed with a rag the particles settle flat and produce a very reflective surface. This will work better on a smooth, dark ground.

Adhesives and solvents

Adhesives

Adhesives differ mainly according to, first of all, the ease with which they find all those microscopic purchase points on surfaces (rather like a rock climber), in other words, how fluid they start or how ‘sticky’ they are. Then it depends upon the means by which they harden, that is, by evaporation of a solvent within or by a chemical reaction. Finally, they differ according to how hard and inflexible they can become.

PVA

PVA is one of the best glues for general purposes, effective on most porous surfaces such as card and wood. The initials stand for ‘polyvinyl acetate’. PVA allows for some repositioning, but relies on surfaces being tightly pressed together to bond. As it dries it contracts, pulling the joint together even tighter. Even when fully dry it will still be slightly flexible and shock-resistant, which is why it’s used commonly in carpentry. It is water-based and dries by evaporation, so will not be effective if air can’t get to it somehow. It also relies on establishing a purchase on a microstructure and being at least partially absorbed, which is why it will not work on plastic or metal (foam is an exception because of its porous nature). Weak gluing between plastic or metal can be achieved sometimes by roughening the surfaces and creating purchase points.

It’s important for the model-maker to distinguish between a concentrated PVA such as wood glue (Evo-Stik Wood Adhesive is a popular make) and the weaker, diluted ‘school glue’ types. Proper wood glue will usually be much more effective and versatile. PVA also serves as a good binder for pigment, as a useful varnish or sealant and, when heavily diluted, as an effective fixative. Standard PVA is not strictly waterproof, although waterproof versions are available. Another special form of PVA worth mentioning here is ‘Hi-Tack’, which is ideal for scattering materials into because it is stickier and slow-drying.

Superglue

A rapid setting glue, which is more effective the less one doses. Superglue (cyanoacrylate) doesn’t harden by evaporation but by reacting with traces of water (specifically ions) to be found on any surface. This is why superglue seems so effective at gluing fingers together while the thing to be glued remains at times blissfully unaffected. This is also why it works so fast. Unlike PVA, it is brittle when hard, so if too much is used between a joint there is the danger that the superglue itself will shatter if jolted. It will achieve a weak bond on metal, mainly for this reason, but this can again be assisted by roughening the surfaces. Accelerators are available in bottle or spray form which will harden the glue even faster on contact. It is better to dose the former using a needle and syringe, while the latter can be both wasteful and harmful because most ends up in the air. Neither superglue nor accelerator is pleasant to have in one’s working atmosphere. If mistakes are made (or fingers welded) ‘debonders’ can be bought which will loosen the glue, but pure acetone will also work.

UHU

UHU was marketed for a long time as a general-purpose glue, although now there are an increasing number of specialized formulations. The ‘classic’ UHU (in the yellow tube) is transparent and viscous. It is very much a ‘convenience glue’, effective in emergencies but not really suitable for precise and clean gluing of delicate elements. It can be better than PVA (and an alternative to superglue) for bonding some plastics and light metals. Standard UHU will dissolve styrofoam (and ordinary foamboard foam), but UHU Por has now been developed especially for these.

Contact adhesive

This type of glue is designed for bonding large surfaces, but can also be useful between elements that are difficult to press and hold together. The glue is applied to both surfaces and left to dry until no longer tacky. When the two parts are then pressed together the bond will be immediate with no need for sustained pressure. Contact adhesives generally contain rubber and they remain fairly flexible when dry.

The solvent within them (usually toluene) evaporates and this is both highly flammable and harmful if inhaled. Good ventilation (and preferably a respirator) is essential when gluing large areas. Established makes include Evo-Stik Impact or Dunlop Thixofix.

Epoxy glues

A typical two-part epoxy glue such as Araldite may be the only alternative to soldering for bonding metal. Equal amounts need to be mixed first and different types will vary in their working/setting times. Once set, the bond is very strong.

Plastic solvent

Plastic solvent is a thin, clear liquid that can be used to ‘weld’ styrene. It is most effective when applied onto the joint and drawn into it. It makes a very clean bond with no visible residue. It can be found in most model shops or obtained from plastics suppliers.

Double-sided tape

This can be useful for gluing large surfaces to each other, especially if you want to avoid warping. It can often be used sparingly, for example placing small strips in key positions. It can also be used for provisional assembly of a construction. A good brand such as 3M will stick well, but cheaper brands vary. If more holding power is needed, carpet tape is a much stronger form.

Spray Mount

This comes in aerosol cans and usually two versions are available: a low-tack spray, which will allow repositioning, and a stronger, more permanent one. Spray Mount is invaluable for gluing large areas of paper or thin card. Other glues will either start drying before the area is coated or will warp the paper. One drawback is that a lot is dispersed around the work area and into the air. Another is that most brands are quite expensive.

Copydex

Copydex is a thin latex glue suitable for bonding fabrics and other extra-porous materials such as cushion foam.

Solvents

Water

Water becomes more effective as a solvent if soap is added, allowing it to penetrate further. For any cleaning purposes in particular this should be tried first before resorting to more harmful substances.

White spirit

Sometimes referred to as ‘mineral spirit’, white spirit is thin, colourless and derived from petroleum. It can be used in place of the more traditional turpentine for thinning oil-based paints and will not affect their drying time. It is flammable and can cause irritation to the skin. It is a good basis for making stains (for example, by dissolving oil pastel or polish in it), or for turning ordinary pencils into aquarelle pencils (see Chapter 7).

Turpentine

This is more expensive than white spirit and is favoured by oil painters. If used to thin enamel paint it will affect the drying time. It is flammable and can cause irritation to the skin.

Acetone

This is the only solvent that will remove cellulose paint (for example, car primer, body spray). Special cellulose thinners are available, composed mainly of acetone. Nail varnish removers contain acetone, but most now have protective ingredients that inhibit its action. Pure acetone is available from chemists or some paint centres. It will dissolve polystyrene, styrofoam (some other forms of styrene) superglue, fibreglass resins and biro ink. Highly flammable!

Methylated spirits

Also known as ‘denatured alcohol’, it has been rendered unfit to drink, hence the mauve colour, which is purely a safety warning. It will dissolve organic resins such as shellac, as well as rubber glue, biro and felt markers. It is very useful for smoothing the surface of polymer clays such as Super Sculpey. Highly flammable!

Lighter fluid

A petroleum spirit, useful for removing some glues such as the residue left by tape. It is also, of course, highly flammable.

Tools

The following list represents the absolutely basic tools. Other tools can always be added, according to personal preference and the special requirements of a job.

Scalpel

This is a precise surgical knife with disposable blades, obtainable from most art suppliers. The standard is from Swann-Morton and the best blades to use are 10A.

Usually two sizes of handle are available, but the smaller is generally easier to use. The advantage of this type of knife over other types (such as X-acto) is that the blade is more supported along its length. Blunted blades can be easily resharpened by stroking both sides on a piece of wet & dry paper (P600 grade or more).

Mechanical pencil

This, as opposed to the traditional wooden type, is essential for delivering a thin, accurate and consistent line. The cheapest ones will serve just as well as any others, though it’s best to get one using 0.5mm leads as these are more commonly available. For marking out, it may be better to use a hard lead such as 2H, but HB is suitable for most other purposes.

Scale rule

The standard three-sided design is the easiest to use, especially if it just displays one scale at a time. Colour coding also helps to locate different scales.

Cutting mat

This serves not only to protect tables and prolong the life of a cutting blade, but also to ensure a non-slip work area. Like the pencil, there is little advantage in getting an expensive one. It should be kept purely for cutting and kept clean; it should not be used for painting or gluing.

Metal ruler

A metal ruler is for measuring but also for cutting against. The best are the simplest; flat strips of steel. The lighter aluminium types (those with the rubber grip) can be too easily damaged. A strip of masking tape along the underside of the simpler type will serve just as well to make it non-slip. It helps to have more than one ruler (preferably 15cm, 30cm and 60cm), because having to wield a long ruler for fine work is both annoying and inaccurate.

Engineers’ try square

This is another essential tool for marking out (see Chapter 2). DIY centres will have inexpensive carpenters’ try squares, but the smaller metal ones are handier. It is also useful to have an adjustable version, also known as a sliding bevel, for marking off repeated angles.

Metal guide blocks

Unfortunately these can’t be bought ready made, but metal stockists may sell offcuts. At least two straight sides are needed, with 90-degree angles (see Chapter 2).

Stanley knife

Although Stanley knives are not suitable for fine cutting, they are useful for some tasks that require a stronger knife. Thin MDF or plywood can often be cut with this knife (especially if the cut is made from both sides).

Fruit knife

The advantage of a fruit knife (which can be found in most kitchen suppliers) over an ordinary penknife for carving soft materials such as styrofoam is that the blade is curved inwards rather than outwards. This makes it easier to shave off thin strips. If used a lot, it is essential to invest in a good sharpening tool.

Saws

The most useful of these is a bead saw, denoting a small blade of thin metal which is reinforced along its upper edge. These are usually fine-toothed and traditional ones (for delicate carpentry) are fixed in a wooden handle. Modern versions often have a detachable plastic handle. Other useful saws for our purposes include a junior hacksaw (for cutting metal) and a coping saw, which has a similar shape and a very slender blade held under tension.

Rasps and files

Most people build up a collection of rasps for wood or files for metal. Model-makers will use them on a variety of materials and all will have some effect. Needle files, for example, are designed for fine work in metal, but they are also excellent for refining details in hardened modelling material. They can also double as soft modelling tools. Rasps or surforms are useful for rough shaping in styrofoam.

Pliers

It is useful to have a few pairs of pliers, including a standard heavy-duty flat nose (preferably with a jaw large enough for bottle tops), a small pair of round-nose pliers (better for bending tight curves in brass rod) and another smaller flat-nose pair with a longer jaw. Although combination pliers include side cutters for snipping wire, it is better to have a separate pair of snippers, or cutting pliers.

Soldering iron

A standard 30W iron is suitable for most model-making purposes, especially if it comes with a choice of bits (see Chapter 4). It must have a stand! Antex or Draper are reliable makes.

Sandpaper

Any sandpaper will work after a fashion, but sanding will be much more effective if the paper is mounted or at least wrapped around a block, especially when sanding large flat areas. The disposable sandpaper nail files available in chemists are invaluable for delicate work.

Brushes

Apart from the usual selection based on personal preference (ranging from fine and precious to rough and disposable), some special types are necessary. Soft, flat brushes are most useful for dry-brushing effects (see Chapter 7). Special brushes are made for stippling paint when using stencils. These are not so suitable for stippling texture as they will clog too quickly and cheap bristle brushes are better. Synthetic brushes may stand up to the rigours of being used incorrectly better than natural hair and are also cheaper. Certain brushes should be reserved (and marked) for particular tasks such as brushing vaseline on prototypes for casting, or applying solvent to styrene (for which natural hair is recommended).

Masking tape

This is a low-tack paper tape used by decorators as a mask before painting. It will hold well, but can be carefully peeled away from most surfaces without damaging them. It is useful for holding down elements while gluing, holding brass in position while soldering or, obviously, for masking areas while painting.