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Fixture Materials

With modern-day technology and manufacturing system innovations, a wide variety of materials are used to construct fixtures used in a residential kitchen or bathroom. The choices vary in price, which are typically based on product quality and durability differences. The kitchen or bathroom designer should be familiar with the manufacturing or the fabrication systems used by the companies they represent to create their products. Because products fabricated out of new materials or manufactured in new ways are continuously being introduced to the marketplace, designers should plan a continuing education project by attending trade organization meetings and exhibitions, by using the Internet to learn about new products, and by meeting with manufacturers or their representatives on a regular basis. With this knowledge, the specifier is more capable of sorting through the various options available and matching the right material for the intended use by the homeowner.

To introduce you to the most popular materials and construction methods used to manufacture fixtures, we have listed the widely used choices in alphabetical order. There is an ever-changing collection of special materials available for unique, one-of-a-kind fixtures today—notably for lavatories. Unique bathing pools/bathtubs are also available. To learn more about these special fixture materials, collaborate with your manufacturing representative and/or manufacturing companies.

• Learning Objective 1: Describe the different materials that kitchen and bathroom fixtures are made of, comparing their durability attributes.
• Learning Objective 2: Provide examples of specialty materials used for bathroom lavatories.
• Learning Objective 3: Identify which materials are most appropriate for sanitary fixtures, such as toilets and lavatories.

PROTECTING MATERIALS FROM BACTERIA

Kitchen and bathroom materials can be protected from bacteria by applying a protective coating on the surface or by including an antimicrobial agent (typically silver or copper) within the material itself. The antimicrobial treatments protect against the growth of microbes, such as bacteria, mold, fungi, and algae, by piercing the thin cellular walls of the microbe. Kitchen and bathroom equipment and surfacing manufacturers typically list the presence of such antimicrobial systems within their product literature.

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Definitions of Terms

• Accessory. Although some accessories are specified for kitchens, they are an integral part of bathroom planning. Towel bars, handrails, toilet paper holders, and various other items that complement the fixtures and fittings are an important part of each bathroom center of activity. Their design and placement are detailed in the Bath Planning volume of the NKBA Professional Resource Library.
• Fixture. A kitchen sink, bathtub, shower, lavatory (bathroom sink), toilet (water closet), bidet, or urinal that receives water.
• Fitting. A faucet, bathtub filler spout, showerhead, body spray, body mist, or other finished piece through which water passes and then enters a fixture. For simplicity, we will use the word “fitting” to refer to all types of water-delivering devices.

Your company may have specific terminology policies. Ask how you should refer to the various fixtures in your specifications. When speaking with a client, use terms that are familiar to the average homeowner, or explain a new name to the client the first time you use it.

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FIXTURE CONSTRUCTION

Cast Iron

You may have heard the term “cast iron” but not know what the term really means. Cast iron actually describes a manufacturing process used for more than a century to produce bathtubs (see Figure 3.1) and kitchen sinks. Molten iron is cast in a sand mold.

FIGURE 3.1 Cast iron alcove bathtub

Courtesy of Kohler Co.

Sand is used to shape the cavity of the mold. Molten iron that has been heated to 2700° F (1482° C) is then poured into a channel, filling the cavity. After the molten iron has cooled and solidified, the sand cast is removed (the sand is recycled), and the exposed product is ready for finishing. The exterior surface must be smoothed to a uniform finish. Once this is done, the final enamel finish coat is added. This finish is a combination of clay, frit, color oxides, and opacifiers. It is applied to the exposed surfaces of the fixture in powder form and then fired at 1250° F (676.67), which melts the powder uniformly into a smooth coating, which fuses to the cast iron base material.

In contrast to an enameled steel fixture, the enamel coating on iron is much thicker and the cast iron is more resistant to movement. Therefore, a cast iron product is more chip-resistant.

Heat Transference

Cast iron fixtures are cool to the touch and thus may be momentarily uncomfortable for the bather as he/she reclines against the backrest above the water line. Because cast iron conducts heat, the bath water will cool more rapidly in a cast iron bathtub than it will in one made out of a plastic material, which has better insulating properties.

Weight Factor

Kitchen sinks and bathroom lavatories are heavy but can be carried by one person. Cast iron bathtubs are very heavy and therefore generally are limited to sizes up to 72 by 36 inches and 60 by 42 inches. Attention to this weight factor is important if you are designing a bathroom that is accessible only up a long flight of stairs. It can easily require four strong men to wrestle a cast iron bathtub up to a second-floor location. Check the manufacturer’s specifications to verify the exact weight of the fixture, and verify clearances to ensure the bathtub can be moved into the bathroom.

Composite

The use of composite kitchen sinks as pictured in Figure 3.2 is growing rapidly. However, because there are many types of composite sinks, there is much confusion in differentiating one from another. In general, the main types are acrylic/polyester, granite, and quartz composite.

FIGURE 3.2 A composite kitchen sink

Courtesy of Elkay Manufacturing Company

Acrylic/polyester. Of all the types of composite sinks available, acrylic/polyester sinks are the lowest performing in terms of scratch and stain resistance, because they are made from soft materials that can cut and nick easily. Yet they are popular because they come in a variety of colors. They also can be integrated into counter surfaces of the same material in matching or contrasting materials.

Granite composite. The most scratch-resistant sink material on the market today is granite composite. They are fabricated with up to 85 percent natural granite particulates. These sinks offer stain, chemical, and scratch resistance. They also offer the highest level of durability because of the extremely high density of rock particles at the sink’s surface. Granite-based sinks are available only in matte finishes.

Quartz composite. With a combination of up to 85 percent quartz and the balance resin filler, quartz composite sinks provide a durable surface. These sinks can resist everyday cuts, scuffs, and dents and can easily stand up to harsh cleaning materials or liquids that might stain other sinks. Quartz composite sinks are available in a variety of colors. Because the color is uniform throughout, the material never loses its original color. As with granite sinks, quartz sinks are available in a matte finish only.

Enameled Steel

Bathtubs and lavatories can be constructed out of enameled steel. This material is fabricated by forming cold steel, then applying a coating of enamel, and finally firing the finished piece in an oven.

To fabricate an enameled steel fixture, a sheet of metal is pressed into a die so it forms the desired shape. This process is called “drawing” because it results in a shape that has depth. The fixture is also subject to mechanical operations, called “stamping,” to cut or form the individual parts of the fixture. Some enameled steel fixtures also require sections to be welded together.

After the form and shape have been finalized, an enamel coating is sprayed onto the fixture. It is then fired in a furnace.

In the showroom, an enameled steel fixture looks quite similar to a cast iron one. However, there are dramatic differences between these two types of fixtures. Enameled steel fixtures are more susceptible to damage than some other fixture materials because when an object is dropped on the fixture, the smooth formed steel will flex on impact. Because of the smooth nature of the enameled finish, it does not follow the movement of the steel and may therefore chip. Such fixtures also require a stainless rim for mounting purposes.

Enameled steel bathtubs are also noisy and good heat conductors, causing bathwater to cool quickly. On the plus side, they are the least expensive fixture you can specify, and they are easy to handle because of their light weight.

Proprietary Materials

In an effort to both maintain the weight benefits and the cost savings of enameled steel fixtures and overcome the material’s susceptibility to damage, major manufacturers have introduced proprietary fixture materials over the last several years. These special materials combine various layers of structural composite backing products (an enamel-grade metal and high-quality porcelain enamel) to provide a lightweight but durable fixture. Pioneered by American Standard 20 years ago as Americast, the manufacturing process forms the layered material in a closed mold manufacturing process similar to an enameled steel manufacturing system but results in a more durable product for the bath because of increased shock resistance. This system is also used for kitchen sinks.

To learn more about the benefits of these special products, read the manufacturer’s literature or consult with a company representative.

Fire Clay

Fire clay is a compound ceramic material that includes prefired clay particles mixed with ball and china clays. The prefired clay particles (called “grog”) are ground into small grains and added to the liquid casting slip, giving it a unique and distinct appearance. Up to 40 percent of the slip can be prefired particles that allow the fired product to be more porous. This extra porosity requires that the fixture have an undercoating applied to the surface before glazing. This extra step in the glazing process gives the finish a deeper color throughout the piece. Fire clay colors—notably white—are typically more brilliant than the colors of cast iron products. The porosity also makes the fire clay more resistant to shock than vitreous ware; therefore, its durability characteristics are similar to cast iron.

Last, fire clay products, as pictured in Figure 3.3, are distinctly different from cast iron in that they are lighter in weight. One of the advantages of the lighter-weight material and less shrinkage in fire clay is that considerably larger pieces can be manufactured with less warpage and crisper design details. However, the porosity makes fire clay products non–code compliant for toilets and urinals—all surfaces containing water must be glazed.

FIGURE 3.3 Fire clay kitchen sink designs

Courtesy of ROHL

Plastics

Novice bathroom designers often are confused by all the terms that relate to bathroom fixtures made from man-made materials. Some fixtures are identified by the reinforcing material used: fiberglass. Other fixtures are identified by the exterior finish material used: acrylic. Still others are identified by the manufacturing process employed to fabricate the fixture: injection molded.

To understand the differences among these fixtures, you must understand the differences between a reinforcing material and a finishing one. In addition, you should be familiar with the different attributes of each of the popular finishing materials.

Regardless of durability differences, all plastic fixtures are warm to the touch and therefore are comfortable for the bather to lean against. When used for a bathtub, these fixture materials act as insulators so the water in the bathtub does not cool as rapidly as it does in a cast iron bathtub.

Acrylic

The first manufacturing approach is to create the fixture by forming it out of to inch sheet of acrylic or acrylonitrile-butadiene styrene (ABS). In this thermo-forming method, the temperature of a thermoplastic material, such as acrylic or ABS, is elevated to a level that makes it pliable and workable; it is then vacuum formed onto a mold, creating the desired shape. All fixtures requiring structural support are sprayed with resin and chopped strands of glass in much the same manner as the fiberglass spray-up method of construction detailed next under “Fiberglass.” The application of reinforcement boards or braces is the same for both materials.

Acrylic and ABS thermal plastics are harder materials than fiberglass-backed polyester gel coated fixtures and the color goes all the way through the material. They also offer deeper color tones and are more resistant to abrasion, high-heat scarring, and sun fading than fiberglass. Although acrylic can be scratched, it is repairable. As you might expect, acrylic fixtures are also more expensive than fixtures finished with a gel coat (see Figures 3.4, 3.5, and 3.6)

FIGURE 3.4 An array of shapes, configurations, and sizes is available in acrylic bathtubs, including jetted versions.

Courtesy of Americh

FIGURE 3.5 An acrylic bathtub under-mounted in a platform

Courtesy of TOTO^® USA, design by Ellen Cheever, CMKBD, ASID, CAPS

FIGURE 3.6 An acrylic shower pan

Courtesy of American Standard

Fiberglass

The term “fiberglass” is used in regard to the backing material used to reinforce a polyester gel coat finishing surface. A mold receives a layer of gel coat, then fiberglass strands immersed in a polyester resin are sprayed on or placed on top of the mold in mat form. Additional reinforcing, in the form of wood or metal strips or braces, is attached at this stage of the manufacturing process.

The polyester gel coat is not as durable as other finish surface layering materials in use today. However, it is generally the least expensive finish and the easiest of the plastic fixtures to repair. Much like cultured marble (cast polymer) products, such fixtures are widely produced by small factories. Therefore, quality levels can vary widely.

Injection Molding

Injection molding is the third method of manufacturing plastic fixtures. The plastic material is heated until it reaches a liquid state, at which time it is injected into the cavity of a mold. With this process, the color you see on the surface goes all the way through the material.

Solid Surfacing

Solid surfacing materials are excellent products for bathroom wall panels and countertops, molded one-piece lavatories, and custom-shaped shower pans as well as kitchen sinks and countertops as shown in Figure 3.7. Freestanding bathtubs are also available in solid surface. Manufactured from acrylic, polyester, or a combination of acrylic and polyester base materials, these homogeneous (color all the way through) materials can be machined by a skilled fabricator and are repairable if damaged. The hard, nonporous surfaces are stain and burn resistant.

FIGURE 3.7 A solid surface kitchen sink integrated into the DuPont Corian^® countertop.

Design by Pietro A. Giorgi, Sr., CMKBD, and Ellen Cheever, CMKBD, ASID, CAPS

There are differences between acrylic-based and polyester-based materials. A more detailed discussion of solid surfacing can be found in Chapter 7.

Stainless Steel

Stainless steel fixtures generally are formed following the same process described for enameled steel fixtures. However, no surface coating is applied to a stainless steel fixture.

Stainless steel quality generally is judged by the steel gauge, the nickel content of the fixture, and the finishing technique.

The higher the gauge number, the thinner the steel.

• A 22-gauge, mirrorlike stainless steel sink is the least expensive and the least desirable stainless steel product. Because of its thinness, it will dent easily, and its mirror finish will show scratches.
• A 20-gauge brush finished stainless steel sink that has a high nickel content will resist water spotting and conceal fine scratches within the brush finish and is thick enough to resist dents.

• The most durable stainless steel sink is an 18-gauge, brushed finish, high-nickel-content sink that has an undercoating on the backside to control noise transmission. Figure 3.8 shows a top-mounted installation and Figure 3.9 shows under-mounted installations.

FIGURE 3.8 A top-mounted (above-the-counter surface) stainless steel sink.

Courtesy of American Standard

a. Courtesy of American Standard

b. Courtesy of Elkay Manufacturing Company

c. Courtesy of Elkay Manufacturing Company

d. Courtesy of Elkay Manufacturing Company

FIGURE 3.9 A variety of under-mounted (below-the-counter-surface) stainless steel kitchen sink configurations.

Vitreous China

Vitreous china is used in the manufacture of lavatories, toilets, bidets, and urinals (see Figure 3.10). It is composed of ceramic materials fired to form a nonporous body; exposed surfaces are coated with a ceramic glaze fused to the body. Vitreous china is used for lavatories and toilets because of its formability and sanitary characteristics. Vitreous china has less than ½ of 1 percent moisture absorption compared to other types of ceramics, such as wall tile, which may have as much as 10 percent moisture absorption.

FIGURE 3.10 Vitreous china is used to manufacture toilets, lavatory sinks, and pedestal sinks.

Courtesy of American Standard

Molded Product

Vitreous china fixtures are a pottery product. To begin the manufacturing process, flint, feldspar, and water are mixed with different types of clays. Once combined, the mixture is poured into a plaster of Paris mold, where it remains during the curing process. The mold is cast from a master mold, which is reused. These molds consist of two sections that form the inside and outside profile of the piece. In solid casting, the mixture is poured into the area between these mold sections. This mixture, called a slip, then conforms to the interior profile of the mold. For thicker elements of vitreous china fixtures, such as the rim of a pedestal lavatory, an alternative method called drain casting is used. This permits the forming of a hollow section without the use of an interior mold.

Quality Standards

When the fixture is removed from the mold, it is inspected for imperfections. Different manufacturers have different definitions of acceptable quality. Generally, it pays to stay with reputable brands and deal only with firms that have a good reputation for quality.

The number of times a plaster of Paris mold is used affects the incidence of imperfections in the fixture. To maintain a high-quality product, first-class manufacturers use the molds fewer times. Some fixture imperfections are repairable. Others are not, and fixtures with these types of imperfections must be destroyed. Therefore, an unacceptable flaw in the tank of a one-piece unit require destruction of the entire fixture. This is one reason why these fixtures cost more than two-piece toilets.

Glaze

After a fixture passes inspection, a glaze is applied. The fixture is fired in a kiln for an average of 24 hours at temperatures reaching up to 2250° F (1232° C). Once the fixture is removed from the kiln, it is inspected again for imperfections in the glaze surface. Fixtures that meet all standards are boxed and shipped.

Decorated Vitreous China

Some vitreous china fixtures are enhanced with the application of a decorative decal, the addition of striping in a precious metal, or the application of an accent color and/or pattern as seen in Figure 3.11. A decal or decorative striping is applied after the china fixture has been glazed and fired. The fixture is then fired a second time. If this additional firing is at 800° F (426° C), the decoration is on-glaze. If the firing is at a higher temperature, the decoration is in-glaze. A fixture with an on-glaze decorative detail will require more care than a typical fixture. To determine just how careful your client must be when using or cleaning the fixture, find out at what temperature the final firing took place.

FIGURE 3.11 Decorated vitreous china fixtures add a touch of elegance to guest bathroom spaces.

Courtesy of Kohler Co.

Wood–Natural

Several manufacturers offer wood bathtubs and lavatories. Wood fixtures generally are constructed from solid strips of oak or teak. Teakwood is considered more desirable than any other species because of its oily composition, which minimizes its expansion and contraction properties. This is why teak is used extensively in marine applications.

Once constructed, the fixtures are finished with a polyethylene coating to protect and enhance the beauty of the wood. To add to the structural integrity of the fixtures as well as to aid in heat retention, the outside of wood bathtubs is generally sheathed in fiberglass.

Wood fixtures should not be exposed to constant, direct sunlight. They need to be wiped down after each use to avoid the development of a permanent, unattractive water line. If damaged, the polyethylene finish can be repaired.

Specialty Materials

Specialized fixtures are also available in spun glass, plastic products, copper, and brass. When specifying these one-of-a-kind items, your product research for these unique designs, typically proprietary, should focus on the manufacturer’s information on sizing, material composition, plumbing/hook-up requirements, and use and care instructions.

Lavatories

Hand painted. Many vitreous china lavatories (below counter, above counter, and pedestal) are part of an artist’s collection that has a beautifully rendered hand-painted pattern.

Glass. Glass lavatories in various sizes are cast by space-age glass products to create unique vessel or over-the-vanity type of lavatories (see Figure 3.12). Glass lavatories begin by bringing the material to temperatures as high as 2200° F (1204° C) so that the molten glass can be manipulated. The glass can be spun or cast. To increase the durability of the product, layers of metallic oxides, such as titanium, silicone, and magnesium, are layered between two sheets of glass, which is then fused into a flat sheet. These unique lavatories are then placed over a mold and heated to the final shape. Because each of these bowls is handcrafted by artists, there will be slight variations in color, layout, texture, and finish.

FIGURE 3.12 Glass vessel lavatories are available in a variety of shapes and forms.

Courtesy of Kohler Co.

Metal finishes. An innovative range of sculptural bathroom shapes is available from several manufacturers in copper, stainless steel, or other specialty metals. Some of these lavatories have what is called a “living” finish and will require constant cleaning; the finish also may change with age. Other metal lavatories are coated so that the original finish protected and will not change if cared for properly.

Figure 3.13 shows how unusual materials such as stone can be specified for bathroom lavatories.

FIGURE 3.13 NKBA Design Competition award winning powder rooms featuring unusual materials

(a.) Design by Lori W. Carroll, ASID, IIDA; codesigners Debra Gelety, Allied ASID, EDAC, and Mary M. Roles. Photo by William Lesch @Lesch Photography

Stone—Natural

Granite or marble slabs may be used to create custom one-of-a-kind lavatories, as seen in Figure 3.13. Typically, these natural stone products are reserved for wall, counter, or floor surfacing in a slab or tile format.

A detailed discussion of surfacing materials and their application is found in Chapter 7.

SUMMARY

The materials used in the manufacturing of fixtures have not dramatically changed over the past five years. The biggest growth in consumer interest is in the specification of composite materials for kitchen sinks and an interest in decorative specialty materials for bathroom lavatories.

Although the basic material categories have not changed, less expensive imported products have gained distribution within North America. Sometimes these products are not as durable as offerings by well-known North American and international manufacturers. Designers can use this information as a generic platform of knowledge as they evaluate new products offered in these various material categories.

REVIEW QUESTIONS

1. What is the difference between a fixture and a fitting? (See “Definition of Terms,” pages 137–138)

2. Identify the two ways a surface can be protected from bacteria growth. (See “Protecting Materials from Bacteria,” page 138)

3. What are the durability differences among cast iron, enameled steel, and fire clay kitchen sinks? (See “Fixture Construction,” pages 138–141)

4. Why is acrylic considered more durable than fiberglass? (See “Plastics,” page 142)

5. What are the manufacturing differences that affect the quality of a stainless steel kitchen sink or bathroom lavatory? (See “Stainless Steel,” pages 144–145)

6. Why is vitreous china considered the most sanitary material for bathroom fixtures? (See “Vitreous China,” page 146)