Restoring Shellac Finishes
A QUICK HISTORY OF SHELLAC AND ITS USE ON FURNITURE
Shellac is a resin that has been refined from the secretions of tiny bugs that grow in India, Thailand and China. For those of you interested in trivia, the bugs are called, Laccifer lacca Kerr, or more simply, lac bugs. Shellac resins come in a range of colors based on the type of tree the bugs feed upon and on the time of year harvested. Shellac has been used for at least a couple thousand years as a dye as well as medicinally and therapeutically in those countries. There are records of shellac being used as a wood finish as early as the 1500's, but widespread use as a furniture finish did not begin until the early 1800's. Then through the first couple decades of the twentieth century, shellac was the coating of choice for fine furniture.
PROS AND CONS OF SHELLAC AS A FURNITURE FINISH
WHAT CAN BE DONE TO RESTORE A SHELLAC FINISH?
One of the most common problems with old shellac finishes is that they are simply dirty. The accumulation of waxes, polishes, smoke and dust, can become so heavy that the the beauty of the finish and the pattern of the wood grain can be completely obscured. This problem can be successfully remedied by virtually anyone. There are solvents formulated specifically for this work, such as the Wax & Polish Remover by Liberon. Mineral spirits, also known as paint thinner, also works well, as do some of the new citrus based cleaners. The technique for cleaning with these is simple. With the solvent, use 0 to 0000 grade steel wool (you will need to determine which will be the best grade for your project). We like the wool made by Liberon best. Wet the steel wool with the solvent and gently scrub the surface. You may start out gently scrubbing with a circular motion but then finish up scrubbing with slightly more force in the grain direction. Wipe the surface down with disposable towels. If the surface is sufficiently clean, you are done, otherwise, repeat this process until the surface is clean.
Since shellac dissolves in alcohol, most damage to shellac can be repaired by either reapplying a new layer of shellac, or by wiping, brushing or misting the surface with alcohol. This is a very simple concept, but the techniques are not as simple as they sound. For example, french polishing, which is a method used for applying a highly polished shellac finish primarily to small table tops, is a technique used successfully only by the most experienced workers. Repairs to french polished surfaces need be be done by people who can successfully apply a french polish finish. Also, the type of alcohol used to repair various types of damage can be crucial. An alcohol used to quickly repair a fine scratch will not repair crazing. Fine scratches can easily be repaired by wiping or brushing, whereas crazing is best repaired by misting or fogging. If more than fogging is required, lightly sand the surface with a very fine sand paper, such as 320 grit. Next apply a thin coat of shellac. Typically this simple approach will yield a beautiful restored shellac finish. Some experimenting on how to apply the shellac would be wise. Padding works bests on flat surfaces, brushing on others. The bottom line is, shellac finishes are repairable, but a trained and experienced worker will have greater success with the repair.
There are a number of formulas circulating for one step "revivers" or "restorers" for shellac finishes. These will employ some combination of three or four of the following materials: boiled linseed (or other) oil, white vinegar, denatured alcohol (metho), turpentine (turps), and sometimes shellac. We have tested some of these formulas and found that they do improve the appearance of the shellac finish. However, the end result has not been as satisfactory as the approach we have been employing, which is outlined above.
There are times when the shellac is so badly worn or damaged, or when a water stain has blackened the wood beneath the shellac, that the finish simply must be removed and a new coating applied. For the best result possible removing the old finish and applying a new, of course you will want to bring it to us. However, you can achieve a good result on your own using virtually any stripping solvent to remove the shellac. Use this link for information on how to remove the finish yourself. Shellac can be applied to the stripped and prepped surface by pad, brush or spray. If you would like to try applying shellac yourself, Zinsser makes a french polishing shellac as well as an orange and white shellac in quart and gallon cans. Zinsser products are available at many hardware and paint stores. Shellac has a short shelf life once liquified, so be sure to check the date stamp on the can. For more choices appropriate especially for antique furniture, Liberon makes a half dozen different premixed shellac polishes of varying colors. Or, if you feel adventuresome, mix your own shellac using shellac flakes and denatured alcohol! If you do decide to try the finishing work yourself, be sure to practice your skills on a scrap before you try working on your furniture item. If you feel very adventuresome, here is a link to instructions for French Polishing.
CARE OF A SHELLAC FINISH
The first step in caring for a shellac finish is understanding what are the potential sources of damage. The chart above provides a reference for what to keep away from shellac finishes, particularly alcohol, ammonia, strong soaps and heat. Doilies can help to prevent scratches. The surface can be kept clean by dusting with a dampened cloth. A weak soapy solution can be used if there are oily marks or smudges that will not come off with damp dusting. Polishes could be used to accomplish an emergency clean and shine, but should not be used for routine maintenance. The adverse and unexpected result of regular polishing is the accumulation of a layer of dust trapped in the polish as it slowly evaporates. If using a polish, it is also essential to verify that the pH of the polish is not in the higher range, for alkalines will degrade shellac.
The best protection for shellac finishes, and the most common method of care used during the time shellac was the furniture finish of choice, is wax. A layer of wax will protect the shellac surface from the minor scratching and scuffing which come during the course of normal use. Further, wax will add a second level of defense against the liquid enemies of shellac. Wax is affected by heat at lower temperatures than shellac, so there is no gain there. Wax will help increase the water resistance of the finish, which is especially important with older shellac finishes which have begun to loose their natural resistance.
Applying a coat of a fine paste wax with an appropriate color blended in will eliminate the discoloration of any nicks or scratches and give the piece an even, soft, satiny sheen. For this we use Liberon's Black Bison paste wax, and strongly recommend that you do too. We have tried every widely regarded wax we have heard of, none are better than Black Bison. Black Bison uses highly refined liquifying solvents and so has a very low and not unpleasing odor. It buffs well and has an appropriate sheen.
Shellac forms a beautiful finish, accentuating the grain of the wood and adding its own warm tone.
Shellac resins are non-toxic.
It is highly water resistant.
It adheres extremely well to virtually everything.
It forms a hard, glossy surface.
It is highly repairable.
Shellac is susceptible to damage from alcohol, strong soaps and ammonia.
Its water resistance diminishes with age.
It can be damaged by heat as low as 120°.
It scratches or shatters easily due to its brittle nature.
It can craze and darken with age.