Shellac is made from the secretion of the lac insect. Proper thinning of the shellac is a vital part of the correct application. The concentration of shellac in alcohol is known as its cut. Most shellac on the market is 4 or 5 pound cut. The cut is indicated on the label. For almost all purposes, shellac will require thinning with alcohol. The proportions are the same if you are thinning a pint or a gallon. For example: “If you wished to thin a pint of 4-pound cut to a 2-pound cut, you would use 3/4 pint of alcohol to 1 pint of shellac”. A 4-pound cut is the best for general use. When thinning, use only pure denatured ethyl or grain alcohol. Before you use shellac, shake or stir it thoroughly. The first two coats should be thinned to a 2 pound cut and the final coat should be 4 pound cut. Shellac comes in three types: orange, ‘bleached’ or white and dewaxed. White is best for most work and orange is used for dark wood or darkly stained woods.
SATIN RUBBED FINISH
This finish is ideal for most furniture. Here are some pointers for applying shellac to obtain a satin rubbed finish:
1. Apply enough coats of shellac so the last one shines. (four or more) Allow time for each coat to dry. Test for drying by trying to make a thumb print.
2. Sand lightly with #400 grit paper. Dust with a brush and wipe with a cloth after each coat.
3.Allow several hours for the final coat to dry completely, then rub with 3/0 steel wool until there is absolutely no shine remaining. After the gloss has been removed by rubbing with steel wool, sprinkle the surface with dry 2/0 pumice and brush lightly. Dust and wipe off the surface and apply at least two coats of wax.
POLISHED RUBBED FINISH
This finish is for high grade furniture that requires extreme smoothness and high polish. Surfaces should be completely smoothed with paste filler before the finish is applied. The steps are similer to the satin rubbed finish but usually six or more coats should be applied. When the entire surface has been completed, wipe it off with soft rags and allow to dry completely. When a highly polished finish is desired, it may be obtained by a final rubbing with rottenstone and a linseed oil mixture after the surface has been completely cleaned. Then apply at least two coats of wax.
An oil finish is one of the oldest for hard or close grained woods. The old-fashioned oil finish is accomplished by using a mixture of two-thirds boiled linseed oil and one-third pure turpentine. It requires from five to twenty coats. The process should be repeated until no dull spots remain. Allow at least two days between the first two coats and from a week to a month between later coats. Each coat must be dried before another coat is applied. Because of the time involved, most do-it-yourselfers would rather use the following method:
First coat: Apply one-third raw linseed oil and two-thirds turpentine. Allow 24 hours to dry.
Second coat: Apply pure boiled linseed oil. Dry for 24 hours.
Third coat: Same as second coat.
Fourth coat: Mix and apply on half ‘boiled linseed oil’ and one half japan drier. While applying, watch for tackiness and rub off with burlap. Complete the finish by rubbing with pumice and oil, then with 3/0 steel wool as described earlier.
Lacquer has replaced varnish ans shellac as finishes in the furniture making field because it is easy to spray and dries quickly for fast production. For the home handyman, the lacquer system isn’t widely used because spray equipment is necessary. If your shop is equipped with an air compressor and a spray gun, it’s fairly easy to learn. Lacquer offers a hard, durable, waterproof surface that will withstand high heat without becoming sticky. The surface is transparent and brings out the beauty of the wood grain when a natural finish is desired. Lacquer is the fastest drying finish ever developed. The drying time is 1 1/2 to 2 hours as compared to quick-dry paints, varnishes, and enamels, which require at least 4 hours.
Spraying Technique: The best spraying method requires a pressure of 30 to 40 pounds. As a general rule, using a spray gun at this pressure, you can get by with a single coat. Before beginning the spraying job, be sure the equipment is clean, and make sure it works properly by trying a test pattern on waste material. Apply the spray in even lines across the surface moving parallel with the work. Handling a paint sprayer is an art that comes with practice. Soon you’ll be spraying like a pro.