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Shellac 101 intro

What In The World Is Shellac?
Shellac is a resinous product of secretions from the Lac insect. The resin is collected from trees in southern Asia. In the unrefined state, the product is called seed-lac and comes in many different shades from deep reddish brown to a golden brown color. After the seed-lac is harvested and cleaned of tree and insect debris, it is refined and formed into sheets, which are then broken into chips or flakes that are sold commercially.

Shellac in one form or another has been in use for possibly many centuries, but has only been used as a popular finish from about 1810 to sometime after WWII when lacquers and quick-drying varnishes started to become more popular. Prior to WWII, shellac was the primary finish for wood cased clocks. It is a durable interior finish that is very versatile in that it has the lowest water-vapor exchange of the finishes. However, it does have certain limitations as exposure to excessive moisture, heat, solvents, acids, and alkali products can damage it. But since clocks are not ordinarily exposed to these conditions, shellac’s performance is excelled only by the beauty it can impart to wood.

Shellac is safe once the alcohol solvent has evaporated and the finish has cured. In fact, it is so safe that the Food and Drug Administration has approved it as a coating for pills and candy.

Why Use Shellac?
Shellac was the original finish applied to nearly all 19th century clocks. It is easy to apply, easy to make, not hazardous to you or the environment, and future generations will appreciate you applying shellac rather than another finish. Shellac exhibits rich warm tones when it is applied to woods popularly used in clock making, such as mahogany, walnut, rosewood, cherry, and oak. Compared to other finishes like varnish (including polyurethane), lacquer, and oils, shellac has the lowest moisture exchange. This is a very important characteristic especially for antiques, because it prevents the wood from expanding and contracting so much when the environment changes.

Types of Shellac
There are quite a few types and grades of shellac. In the dry form, shellac comes in flakes, granules, or buttons. The most popular of these is the flake form as it dissolves quickly in the solvent.

Blonde shellac is a highly processed form of shellac that has the wax and natural dye removed. The use of blonde shellac is applicable when a water clear finish is desired on woods such as maple. However, orange shellac is a better choice for clocks.
Orange shellac is the most popular color used, and is easy to apply by padding since it doesn’t have as saturated color as some of the deeper shades. The wax-bearing types of shellac contains a trace of wax, which settles out when you mix it yourself. Orange shellac has a natural warm orange tint that is able to impart a beauty to wood, and especially to antique items like clocks. It’s a shame that more people have not discovered the benefits of using shellac, since shellac and wood go together like butter goes with toast. Lately, I have been using dewaxed orange shellac. It produces a more translucent finish. Since it has no wax content, there is no wax that settles to the bottom of the container. This means the shellac doesn’t have to be decanted off like the waxy variety of shellac. Dewaxed shellac flakes should be kept below 80 degrees F to prevent clumping. If it does clump, no matter, it is still useful.

Other colors of shellac include garnet, button, and dark. In most instances these are too dark as an antique clock finish.

Seedlac shellac was most commonly used in the 19th century by woodworkers. Seedlac is the least refined and contains bug and tree parts, does not have the dyes refined out, and has a high wax content. Seedlac is a popular among conservators as it closely approximates the old type of finish.

Storage
You can buy it pre-mixed from paint stores or hardware stores, but since shellac has a shelf life of 6 months to 2 years, depending on storage conditions, it is best to check the date on the container before buying. Just like buying milk, you’ve got to check the date. The flake form does not have a shelf life until it has been mixed with a solvent. On the other hand, blonde shellac has the shortest shelf life. Dry form blonde shellac has a shelf life, unlike the other types.

Once mixed with the solvent, the shelf life can be extended by storing the mixture in the refrigerator. Wide-mouth glass canning jars work well since they are air tight containers. The glass container allows you to see when the shellac has fully dissolved, and when any wax has settled to the bottom. Shellac should not be stored in metal containers because the acidity of liquid shellac will cause a reaction with the metal and will darken it.

To check the freshness of shellac, put a drop or two of the liquid form on a hard non-porous surface like glass. Allow it to dry for an hour. If you can make a dent with your fingernail in it, then discard it and make a fresh mixture. Old shellac will never fully harden.

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