MAKING GOOD WINE AT HOME doesn’t require an extensive education in chemistry or other microbiological sciences, but gaining a basic understanding of what is going on and how, why, and when to test and adjust your wine is vital. Once again, there are some great books on the market that will present the basics and the details of wine analysis. Here, we are going to set up your lab, make some of the testing equipment for a fraction of the cost of store-bought versions, and get you organized to analyze your wine efficiently.
There are a couple of pieces of equipment that the winemaker uses to determine the amount of sugar in grapes, juice, must, and wine. One is a hydrometer, the other a refractometer. A hydrometer is a long glass sealed tube with a weighted bottom and graduated markings along its upper portion. Most winemakers commonly use the triple-scale hydrometer, which indicates specific gravity, degrees Brix, and potential alcohol. I recommend that every winemaker have a good-quality hydrometer. That said, hydrometers tend to break at the worst possible times, and depending on where you live, it can take a long time to get a replacement. Therefore, you may need to make one in a pinch.
WHILE FAIRLY RUDIMENTARY, this simple DIY hydrometer will get you through until you have a replacement manufactured hydrometer in hand.
• One approx. 12″-long drinking straw or other rigid plastic tube (a broken plastic racking cane works too)
• Modeling clay, Play-Doh, glazing compound, or other moldable material
• Distilled water
• Sugar
• Jar
• Graph paper
• 12″ ruler
NOTE: If you’re stuck and don’t have any modeling clay, you can make a bit with ¼ cup of flour, ¼ cup of warm water, 1/8 cup salt, and ¾ teaspoon vegetable oil.
Stick a blob of the clay on the bottom of the tube. You might also want to put a very small amount in the top of the tube to keep liquids out.
Lower the tube into a full jar of distilled water. The water line should be near the top of the tube. If not, add more clay to the bottom of the tube to weight it down. The correct amount to add is just enough to sink the tube to within ½″ of the top of the water. Mark the water line on the tube with a permanent felt-tip marker; this is the 0° Brix mark. Remove the tube and dump out the water.
Mix up a solution of 24 grams of sugar in 100 ml of distilled water. Fill the jar to the top with this solution and lower the hydrometer into it. Allow it to come to rest and mark the water line with the marker. You now have it marked for 0° Brix and 24° Brix.
The Brix scale is a straight-line scale, so you want to mark the straw from 0 through 24. Rather than doing the math, set the hydrometer on a piece of graph paper and note the 0 and 24 marks. Place a ruler on the graph paper at an angle so the 0″ mark of the ruler aligns with the graph grid line of the 0°B mark on the hydrometer and the 12″ mark aligns with the 24°B grid line. Transfer every half-inch mark of the ruler down to the hydrometer and mark it on the tube. Then just number every fourth calibration mark from 0 through 24 and it’s calibrated.
Whether you are using a DIY hydrometer or a glass hydrometer, float the device in relatively clear liquid in a hydrometer jar (a clear tube just a bit larger in diameter and taller than the hydrometer).
NOTE: Hydrometer jars are very cheap, so I recommend just buying one with your hydrometer. If you’re stuck without one, however, put a wine cork in a 14″-long piece of clear plastic tubing and cut the cork off flush with the bottom of the tubing. For a base, drill a ¾″ hole though a 2″ square or circle of ½″ plywood, and glue the tube into the hole.
Q Drawing a sample of fermenting red wine for checking sugar levels is fairly difficult due to all the skins and MOG (matter other than grapes) in the must that clog up your wine thief. Plus your sample should have as few solids in it as possible to get an accurate reading. A trick I’ve found that allows for obtaining a clean sample is to punch down the cap just prior to drawing the sample, place a stainless steel kitchen strainer on top of the must, and pull the sample with a turkey baster.
FIGURE 5.7 DIY Hydrometer
The refractometer is the other device that winemakers use for measuring sugar. This instrument is a calibrated prism that refracts light and indicates the amount of sugar present in the juice. You put a couple drops of the juice on the prism, close the cover, look through the scope, and read the scale. As your must is fermenting, alcohol will skew the reading, so you need to refer to a compensation chart to obtain the actual reading.
As is the case for any piece of equipment, calibrating your refractometer is critical to obtaining good results.
A refractometer is very handy for field testing in the vineyard. You take a very random sampling of grapes that are going to be picked together, put them in a small ziplock bag, and mush them up and mix well. Then snip a corner from the bottom of the bag, let a few drops of juice fall on the prism, and read it.
As is the case for any piece of equipment, calibrating your refractometer is critical to obtaining good results, so at the beginning of each season, make up a standardizing solution of a known amount of sugar in grams mixed with 100 ml of distilled water and take a reading with your hydrometer. Use this solution on your refractometer and adjust the calibration to match the hydrometer. Some winemakers I know have several hydrometers and measure the same solution with all of them, then average to arrive at their refractometer calibrations. You should also calibrate at zero with distilled water placed on the clean prism.
Note that some refractometers compensate for temperature while others do not, so follow the manufacturer’s instructions for adjusting your readings if needed.
The pH of a solution gives the winemaker an indication of its relative acidity. A wine with too low a pH will be tart, bitter, or “green” tasting, and one with too high a pH will be flabby and not capable of long-term storage. Getting grapes with the proper range of pH for the varietal is great but not always possible, particularly for a home winemaker.
You can measure pH using paper litmus strips, but they can be difficult to read with a colored wine, and they don’t provide the real accuracy you will need for pH determination and the other tests you will be using this measurement for. Therefore I recommend that all home winemakers consider a good-quality pH meter as essential a piece of equipment as their hydrometer.
A pH meter is an electronic device that has a small glass probe at the bottom of a shaft. Typically it has a couple of calibration screws and a digital readout.
There are a few types of pH meters to be aware of when you’re looking for the one that is right for your needs. One is a penlike all-in-one meter that is very handy for checking pH in the vineyard or whenever it is important to have a pocket-size meter. Due to its low price, it’s a good meter to get when you’re first starting out with winemaking, and it makes a great backup meter as you get more advanced.
Another type is a handheld model with a cable that extends from the electronics module to the probe. A third type is a benchtop model that is larger and typically much more expensive than the other two. The pen-type and handheld models are typically powered by batteries, and the benchtop model more commonly uses 12V DC power.
Your pH meter should have the appropriate range, accuracy, and resolution for winemaking. The range should be from 0.00 through 14.00, the accuracy should be +/- 0.01 pH, and the resolution 0.01 pH. Temperature compensation is desirable but not absolutely required.
The glass probes of the pH meter are very sensitive and can be damaged if they dry out or are exposed to oils on your fingertips. Some manufacturers will void the warranty if their probe is allowed to dry out, so take care to keep it submerged in the appropriate solution, such as a pH probe storage solution, tap water, or a pH 4.0 buffer solution. Do not store a pH meter in distilled water, as it will damage the probe. Follow the manufacturer’s directions for maximum longevity of your probe.
When you first get your meter, you’ll want to follow the manufacturer’s instructions for calibrating it. Know that it will take an hour or more simply for the meter to stabilize and come to rest at a steady reading. Then you can calibrate it. This is done by inserting the probe into standardizing buffer solutions of pH 7.01 and pH 4.01. These solutions need to be fresh and so generally are not used more than once, unless the calibration is being done only a few days after a previous calibration. One manufacturer recommends keeping the standardizing buffers from the previous calibration to use as a prerinse for the meter, before you insert it into fresh buffer solution. I keep used buffer solutions in small, dark-colored bottles for this purpose. A calibration should be good for a week or two, but if it has been longer than that since you used your meter, it’s good practice to recalibrate it.
Handheld and pen-type pH meters
The standardizing buffer solutions are available in bulk or in individual sachets designed for single-use applications. If stored properly, the bulk solutions should last a reasonable length of time for a frequent tester.
Titratable acidity (TA) is a measurement of the acidity in your juice, must, or wine, based on the concentration of the acid in solution. It’s read in grams per liter or percent. For example, the TA of a must might be 7.2 grams per liter (also parts per million) or 0.72%.
The primary chemical for testing TA is 0.10 normal sodium hydroxide (NaOH). (“Normality” is a way to express the concentration of a substance in solution.) You can purchase this solution premixed, or you can make it by dissolving 4 grams of solid-form NaOH in 100 ml of distilled water. Caution: Use lab gloves and goggles when using solid NaOH and read all MSDS sheets. This solution is fairly stable and should last about a year. Before using this solution, it is good practice to standardize the actual concentration of the NaOH; see Standardizing Sodium Hydroxide Solution on page 107.
Ask a dozen winemakers how they test for TA, and you’ll get a dozen different protocols. This is how I do it:
1. Place 100 ml of distilled water into a 250 ml beaker, Erlenmeyer flask, or comparably sized glass jar.
2. Add 5 ml of wine sample to the distilled water, and mix thoroughly by stirring or swirling.
3. Place the pH meter probe in the water and wine solution.
4. Fill a 10 ml pipette or syringe with the NaOH solution, noting the exact amount in the pipette or syringe. Slowly add drops of the NaOH solution to the water and wine solution, swirling after each drop to mix it in, until the pH meter reaches 8.20.
5. Check the pipette or syringe to find out how many milliliters of NaOH you added to the wine and water solution. Multiply this number by 0.15, giving you the percent of titratable acidity.
If your standardization of the NaOH proves your actual concentration is not 0.10N (normal), then use this formula to calculate the TA instead:
VNaOH × N × 7.5/Vs
where:
VNaOH = volume of NaOH used in ml
N = normality of NaOH
Vs = volume of wine sample used
WHEN MAKING TITRATIONS AND OTHER TESTS, a lab support stand is handy to have around. This version consists of a steel rod and heavy base to which you can clamp different pieces of equipment.
• One 8″ × 12″ piece ½″ plywood or HDPE plastic
• One 16″ length 3/8″ solid steel rod
• 3/8″ thread-cutting die with handle
• Two 3/8″ nuts
• Four rubber cabinet door bumpers
Drill a 1/8″ hole in the plywood or HDPE, centered on the 8″ dimension and ¾″ in from the edge. If you’re not using a drill press, work carefully to drill a straight, perpendicular hole. Now, using the 1/8″ hole as the centerpoint, and using a 5/8″ spade bit, drill a hole 3/16″ deep into the bottom of the plywood or HDPE. Do not drill this hole too deep. It’s meant to allow you to recess the bottom nut of the steel rod into the stand base. Complete the hole by enlarging the 1/8″ hole, drilling all the way through with a 3/8″ straight bit.
Q If you use plywood for the base of your lab stand, you can paint it after drilling the hole for the stand. I prefer white paint, as it makes it easy to discern color changes in solutions.
FIGURE 5.2 Lab Support Stand
On one end of the steel rod, use the die tool to cut threads up to ¾″ up the rod. Install one of the nuts at the top of the threads. Insert the threaded end of the rod down through the 3/8″ hole, install the other nut on the rod, and tighten it up into the recessed base hole.
Install a cabinet door bumper at each corner on the underside of the base, and your stand is ready for use.
You can purchase (or make) a number of different types of clamps that work well to hold various types of test tubes, pipettes, burettes, pH meter probes, and so on. You should have at least two of these clamps, and a third could be useful.
Malic acid is one of a number of acids commonly found in grapes. It produces a crisp “green apple” flavor, and depending on your style of wine, this may not be desirable. Winemakers frequently inoculate their wines with malolactic bacteria to ferment this malic acid, which converts it to a smoother, almost buttery-tasting lactic acid. When the fermentation appears to be complete, it’s time to test for malic acid to confirm the process is complete before adding potassium metabisulfite to protect the wine.
THIS TEST IS FOR ANY WINES you wish to put through malolactic fermentation (MLF). It’s easy to perform and gives you a colorful, almost artistic result. You can buy a malic acid test kit, which should include everything you will need, or you can assemble the pieces and reagents from various sources. Chromatography solvent emits strong fumes, so perform this test in a well-ventilated area.
• Chromatography paper
• Capillary tubes
• Malic, tartaric, and lactic acid chromatography standard solutions
• Chromatography solvent
• One 1-gallon widemouthed plastic or glass container with lid (approx. 8″ tall)
• Stapler
Mark a light pencil (not pen) line along the chromatography paper’s long dimension, about ¾″ in from the edge. On this line, mark a series of small Xs, beginning about ½″ in from the left edge and spacing them 1″ apart. You’ll place the standard solutions of tartaric, malic, and lactic acids at the first three Xs, so mark a T, M, or L under them. Under the remaining Xs, identify each of the wines you will be testing.
Collect very small samples of each wine you will be testing. Small paper cups labeled with a felt-tip pen are handy for this.
Fill a capillary tube about half full with your first wine sample; just place the end of the tube in the wine, and it will fill by itself. Put your finger over the upper end to hold the wine in the tube, set the tip of the tube on the appropriate X on the paper, and allow the wine to soak into the paper to form a dot no bigger than ¼″. Repeat this process for each wine sample and each acid solution standard; use a fresh tube for each wine sample. Allow these dots to dry, and repeat this application at least two more times with each sample, taking care to keep the dots no bigger than ¼″. This multiple application concentrates the sample and gives a stronger result.
While the samples are drying, pour about ¼″ of the solvent into the gallon container, taking care not to breathe the strong fumes.
Once the samples are dry, roll the paper into a circle, with the two edges butted together, and staple them to form a tube. With the pencil line horizontal and on the bottom edge, lower the paper tube into the gallon container so the edge is completely immersed into the solvent. Close the container, and wait for the paper to absorb the solvent all the way up to its top. This usually takes 8 to 12 hours, but it can take more or less time. Do not let the paper sit in the solution longer than is needed for the solvent to reach the top of the paper, or the samples may be diluted or encroach on each other.
Remove the paper and hang with a clip (perhaps on the lab support stand; see page 97). Allow it to dry, which can take as long as 24 hours. Once the paper is dry, examine it. Above the tartaric, malic, and lactic acid standards, you’ll find a yellow blotch at a particular height. Look for similar yellow blotches above your wine samples. A blotch at the level of the malic acid standard blotch indicates that malic acid is still present in your wine, and malolactic fermentation has not finished. A blotch at the level of the lactic acid standard blotch, with no blotch at the level of the malic acid standard, indicates that malolactic fermentation is complete.
The chromatography solvent is very stable and will last indefinitely, so once the test is completed, pour the unused portion back into the solvent bottle.
Q Instead of using disposable capillary tubes, you can obtain a small hypodermic needle from your doctor and rinse it with distilled water between uses.
Q For individual samples, cut a 1″ wide piece of the chromatography paper, and place the sample at the bottom as described above. Stand the paper in a 100 ml graduated cylinder with ¼″ of the solvent. Cover with a cork or other top to contain the fumes.
MOST CHROMATOGRAPHY TEST KITS supply you with a plastic jar for soaking the paper in solvent, but the jar is usually opaque, which makes checking on the absorption of the solvent difficult. Using a clear glass jar instead can help, but even so, the jar takes up a fair amount of room for a test that you’ll do only once or twice a year. So, as an alternative to the jar, I have developed this thin-profile chromatography chamber.
• Various scraps ¼″, ½″, and ¾″ plywood
• One 12″ × 12″ piece 1/8″ clear Plexiglas
• Wood glue
• 7/8″ brads
• One 18″ length ½″ PVC pipe
• One ½″ PVC cap
• PVC adhesive
• One ½″ PVC elbow
• One piece chromatography paper
• Wine bottle cork
• One ¾″ rubber stopper
• Two thumbtacks
1. Cut the chamber box parts.
Cut the base of the chamber from ¾″ plywood at 1½″ × 11″. Cut the two sides from ½″ plywood at 1½″ × 10″. Cut the top from ½″ plywood at 2″ × 11″.
Set your table saw blade ¼″ above the table, and use it to mill a 1/8″-wide, ¼″-deep groove along the long dimension, ¼″ in from one edge, on each of these four pieces. On the top piece, cut a similar groove on the other long side, and widen it with another pass or two of the saw to make it slightly more than ¼″ wide. This groove will slip down over the back of the chamber.
Cut the back from ¼″ plywood at 11″ × 11″. Cut the Plexiglas down to 10½″ × 10½″.
2. Assemble the chamber box.
Glue and nail the side pieces to the base, then glue and nail the back to the sides and base. The back should extend ¼″ above the sides. Slide the Plexiglas down into the 1/8″ grooves of the sides and base. Apply some compatible adhesive into the 1/8″ groove in the top piece, and slip it over the Plexiglas and back panel and onto the sides. Let the adhesive dry.
3. Create the solvent reservoir.
Make a mark on the PVC pipe 11½″ from one end. Measure the outside diameter of the pipe, and set the fence of the table saw so that it is half this distance from the center of the blade. Set the blade so that it is just high enough to cut through only one wall of the pipe. Cut a slot in the pipe up to the 11½″ mark; when the blade gets to that mark, carefully lift the pipe up off the blade, starting from the end in your hands and keeping the leading end firmly on the table until the pipe is clear of the blade. Use caution that the pipe does not kick back at you while performing this maneuver. Install the PVC cap on the cut end of this pipe, using PVC adhesive.
Measure the diameter of the PVC cap and drill a hole at the bottom of the right-hand chamber side piece, just above the base, to receive the pipe. Cut the pipe off at 10¼″ (including the cap), and use PVC adhesive to install the PVC elbow on the uncapped side, with the slot in the pipe and the free end of the elbow both pointing up. Slide this solvent reservoir assembly into the chamber.
4. Add paper supports.
Remove the Plexiglas front and chamber top. Set a sample piece of chromatography paper in the slot of the reservoir and mark the top edge of the paper on the back panel. Cut two 1″ × 1″ pieces of ¼″ plywood, and glue them to the back panel at the marked line. Then cut a ¼″-thick piece from each end of the cork, and glue them to the plywood pieces.
FIGURE 5.3 Chromatography Chamber Assembly
Prepare your chromatography paper as outlined in the malic acid test project (page 99). Pull the PVC reservoir partway out from the chamber, and pour the chromatography solvent into the elbow to fill the reservoir half full. Plug the top of the elbow with the ¾″ rubber stopper, and slide the reservoir back into the chamber. Slip your test paper into the slot in the reservoir, so it touches the bottom. Secure the top of the paper in the chamber with thumbtacks pushed into the corks. Install the Plexiglas front and let the test run its course.
Once the solvent reaches the top of the paper, remove the front and, without removing the thumbtacks, gently slip the paper out of the reservoir. Pull the reservoir out of the chamber, and return the unused portion of the solvent to its bottle. Replace the Plexiglas front to allow the paper to dry overnight.
Sulfites (SO2) have been shown to be an excellent addition to wines to preserve them, stop bacterial and unwanted yeast growth, and remove oxygen and other undesirable elements. Sulfites can be added in the form of potassium metabisulfite tablets (commonly known as Campden tablets) or potassium metabisulfite powder. There is much information about the use of sulfites in winemaking on the Internet and in winemaking books and magazines, so here we’ll just explore when and how to perform the testing for free SO2.
Some assumptions I make about sulfites are:
» At crush there is virtually no free SO2 in the must.
» Depending on the type of grape (white or red), the pH of the must, and/or the condition of the grapes, an addition of potassium metabisulfite or Campden tablets should be made at crush to preclude a case of the wine-tainting nasties. This addition would normally range between 35 and 50 parts per million.
» Upon completion of fermentation, nearly all the SO2 will have either become bound or blown off in gaseous form. If malolactic fermentation (MLF) is to be conducted at this time, no additional SO2 is added until MLF has completed. The pH is then checked and SO2 is added (in amounts appropriate to the wine type and pH), assuming there is no residual SO2 in the wine.
» At each subsequent racking, restore the sulfite level to the level determined to be appropriate. At this time it is good practice to perform a test to determine the residual amount and the addition that should be made to restore the desired level.
PERFORMING THE TEST FOR FREE SO2 IS FAIRLY SIMPLE as long as you have the appropriate equipment. A commercially available setup to determine sulfite levels by aeration/oxidation can cost as much as $500, although some manufacturers (having realized that it is easy to make such setups from basic materials) now offer setups for closer to $100. Still too rich for my blood, so here’s how to make one for even less (much less). In addition to the materials listed below, you should also have a 10 ml syringe and 10 ml pipette and pipette bulb handy.
• Two 4-6 oz. glass jars
• Two 2-hole rubber bungs/stoppers to fit the jars (with ¼″ holes)
• One 12″ length ¼″-O.D. (outside diameter) glass tubing
• One aquarium air pump
• One 24″ length ¼″-I.D. (inside diameter) flexible plastic tubing
• One egg timer (or other 10-minute timer)
NOTE: You can make your own two-hole bungs from silicone; see page 89. Use ¼″ plastic tubing for the holes. And if you prefer, you can substitute for the jars with 200 ml #32 test tubes and rubber stoppers supported by your lab support stand (see page 97).
• 3% hydrogen peroxide solution (available at any drugstore)
• Methyl red-methylene blue indicator solution (from wine or chemical supply stores)
• 25% phosphoric acid solution (available from hardware stores in the tile department, or from chemical supply stores)
• 0.01N NaOH (dilute 0.10N solution, one part 0.10N NaOH to nine parts distilled water)
1. Prepare the glass tubes.
Set up the two jars with rubber bungs seated snugly in them. For the purposes of this design, we’ll call the jars Jar #1 and Jar #2, with Jar #1 assigned to receive the wine sample. Be sure the holes in the rubber stoppers will snugly accommodate the glass tubing.
For each jar, cut a length of glass tubing so that it extends from just above the bottom of the jar, through the hole in the stopper, to just about ½″ above the stopper. To cut the tubing, score it with a file or sharp knife, then hold it in both hands with your thumbs on each side of the score mark and quickly snap it. Cut a third, short piece of glass tubing that is about ¾″ longer than the height of the stopper.
Use a propane torch (or other gas flame) to melt one tip of each of the two longer glass tubes to make the hole very small, but not closed up. Hold the tubing with leather gloves or pliers so you don’t burn your fingers. These lengths of glass tubing will serve as impingers.
2. Assemble the setup.
Insert the impingers through one of the holes in each stopper. Insert the shorter glass tube through the other hole in Jar #1′s stopper. You may want to use some lubricant like petroleum jelly or mineral oil to help with this.
Connect the aquarium pump tubing from the short glass tube in Jar #1 to the impinger of Jar #2. Connect the pump to the impinger in Jar #1, and you’re ready to start the test.
Start by taking the pH of your wine sample; you’ll adjust the SO2 based on the pH.
Place 10 ml of the 3% hydrogen peroxide into Jar #2. Add three or four drops of the methyl red-methylene blue indicator solution. Swirl well to make sure it is mixed thoroughly. This solution should be a light pink color. Now add a drop or two of the 0.01N NaOH, until the solution turns a light bluish gray color. Put stopper (with impinger) on Jar #2.
Place 20 ml of wine into Jar #1. Measure out 10 ml of the phosphoric acid, and turn on the aquarium pump. Add the phosphoric acid to the wine and immediately put the stopper in the top of the jar, and the test has begun. Start the timer and let the air from the pump bubble the solutions in both jars for 10 minutes. As you do this, Jar #2 will trap the free SO2 in the solution and will turn it back to the pink color. (Note: if the solution does not change color, it most likely has no residual free SO2.)
Fill a 10 ml pipette (with pipette bulb on top) with the 0.01N NaOH solution, taking note of exactly how much NaOH it contains. Once the time has elapsed, turn off the pump and titrate the pink hydrogen peroxide solution, swirling the solution after each drop of NaOH. When the solution returns to its bluish gray color, stop titrating, and note the volume of NaOH you used in milliliters.
To determine the amount of free SO2 in the wine in parts per million, multiply the volume of NaOH (in ml) used in the titration by 16. Subtract this amount from the desired level for your wine, and add potassium metabisulfite accordingly.
Q If your NaOH solution proves to be different from 0.01N after standardizing, use this formula to determine free SO2:
Free SO2 (ppm) = N × VNaOH × 1600
where:
N = normality of NaOH
VNaOH = volume of NaOH used in ml
EVERY LAB SHOULD BE EQUIPPED for weighing reagents, additives, and other items. A digital scale is helpful, and there are some interesting spoon scales on the market now. You can also make this nice scale that’s accurate to 0.5 gram using scraps lying around your shop. This may not be adequate for very small SO2 additions, but for most other measurements it is perfectly functional.
• Scrap ½″ plywood
• Wood screws
• Scrap 1/8″ plywood
• One small, squat plastic cup (with a volume of about 6 fluid ounces)
• Heavy string
• One paper clip
• One clothespin
• One 1¼″ 3d finish nail
1. Build the scale structure.
Cut two pieces of ½″ plywood at 1″ × 6″, one piece at 12″ × 3″, and one piece at 1″ × 1″. Glue the 1″ × 1″ piece to one end of one of the 1″ × 6″ pieces to serve as a shim block. Screw the 1″ × 6″ pieces into the long side edge of the 12″ × 3″ piece, near each end, to form the uprights of the scale.
Cut the 1/8″ plywood on a long diagonal to create the balance arm. The actual dimensions aren’t terribly important, but it should be about 12″ to 15″ long. Drill a hole near the wide end of the balance arm where you want the cup to hang.
2. Add the cup and clothespin.
Measure around the top of the cup and mark it in thirds. Just below the rim of the cup, at each mark, drill or punch a small hole large enough for a double piece of the string.
Cut three lengths of string about 12″ long. On both ends of the strings, tie an overhand loop knot, ensuring each string is the same length and short enough to allow the cup and strings to hang freely from the balance arm. For each string, push the loop through one of the holes in the cup, then run the other end of the string through the loop. Bring the three strings together at the top and tie them together.
Bend one of the paper clips to form an S hook, and use it to suspend the cup (via the knotted strings) from the hole in the balance arm. Attach a clothespin to the bottom of the balance arm, about 2″ from the S hook. Pick up the balance arm between your thumb and forefinger (or use a pair of calipers if you have them), holding it near the top edge and between the S hook and the clothespin. Move your thumb and finger to find the balance point, where the arm feels relatively level. If necessary, you can move the clothespin a bit or trim a bit off the arm. Once you get a good approximate balance point, mark it, and drill a 1/8″ hole through the arm at that point. The location doesn’t have to be precise, as we’ll set the clothespin at the balance point next.
Drive the 3d finish nail into the center of the 1″ × 1″ shim block, but not all the way through both pieces, ensuring the nail is perpendicular to the block’s face. Then slip the balance arm over the nail. Mark the top of the balance arm on the upright from which it is suspended. Remove the balance arm and measure the distance to the mark you just made. With the whole assembly sitting on a level counter, mark the other upright the same distance up and make a “balance” mark.
3. Calibrate the scale.
Replace the balance arm on the upright, making sure it’s not touching the uprights. Find the sweet spot for the clothespin to perfectly balance with the cup. Once you have it balanced, mark the cup side of the clothespin on the bottom of the balance arm as your zero grams spot. Then calibrate additional points along the balance arm by using a U.S. nickel for a 5-gram weight, a penny for a 2.5-gram weight, and a standard-size #1 paper clip (uncoated) or U.S. dollar bill for a 1-gram weight. A standard business card (not a thick one) also weighs 1 gram, so for a 0.5-gram weight, cut a card in half.
You can use water for additional units of measure, knowing that 1 milliliter weighs 1 gram and pipetting various volumes into the cup.
Once you have the arm marked in 0.5-gram increments, you have a handy little scale for use in your wine lab.
To weigh an unknown amount of material, place it in the cup and move the clothespin to balance the balance arm at the balance line on the left upright. To measure out material to a preset weight, place the clothespin at the desired weight and fill the cup until the arm is balanced. Pouring from a larger container into the small cup can be difficult, so try placing your dry material on a folded piece of paper before pouring it into the cup. For wet material, a pipette, syringe, or small turkey baster will do the trick.
