ShellacShellac has been used as a finish for hundreds of years. Woodworkers like it for the beautiful tone it gives to wood. It also helps that it is easy to apply and easy to repair. Lac is naturally waxy. Different grades of shellac remove various amounts of that wax. If you are using shellac under another finish it can be important to use de-waxed shellac. Some finishes will adhere to any shellac, but with others the wax prevents bonding. I don’t know enough about finishing to know which ones are safe to use, so I just use de-waxed shellac if I’m using it in conjunction with another finish.
You can buy shellac ready mixed or you can make your own. The label on commercial brands should tell you whether it is de-waxed or not. To make your own you buy shellac flakes and mix it with denatured alcohol. The flakes will be marked de-waxed or not.Shellac has a definite shelf life. If you are buying it pre-mixed look at the date on the container. Different brands add agents to extend the shelf life. I mix my own, so I’m not familiar with the different brands. When I mix my own I make enough for whatever project is on hand, or sometimes if i know I’ll be using it later I’ll make enough for a couple months. If you aren’t sure if the shellac is old brush it on a board and wait a few hours. If it’s still tacky chances are it won’t ever dry. Toss it and try again. The advantages to mixing your own shellac are that you know how old it is and also you can get a wider range of colors if you buy flakes. Shellac ranges from “super blond” (clear), to garnet and amber. Colored shellac can give a real depth and warmth to wood. I especially like garnet shellac on walnut, it brings out the richness of the wood.
Another advantage of mixing your own shellac is you can decide how diluted to make it. The mix is identified by the ratio of alcohol to shellac, called “cuts.” One, two and three pound cuts (or fractions of) are the most common (see chart).
or for smaller quantities:
I’m not particularly precise when I mix shellac (truth be told I tend to wing it), but in general I use a 1 pound cut as a wash coat, 2 or greater pound coat for follow up and building the finish. To mix the shellac, first crush the flakes to help them disolve. Put them in a clean plastic or glass container and add the appropriate amount of alcohol. Mix thoroughly and set aside. I usually leave the container on my bench and give it a shake when I think of it. I let it sit overnight and by morning it’s good to go. The darker shellacs tend to have more wax. However, it’s easy to filter it out. If you are mixing your own you can wait until it settles then strain it through a coffee filter. The final mix should be clear rather than cloudy. Shellac can be brushed, sprayed or wiped on. The trick is to use a high quality brush or a lint free rag (I’ve never sprayed it, so you’re on your own there) and apply the shellac in long, slightly overlapping, strokes. If you find that your rag or brush is dragging by the end of the pass it means the shellac is too thick. Dilute it slightly with alcohol and try again. If you hate the look you can wipe it off with a rag dipped in alcohol. The same applies to repairs. If you get a scratch you can wipe it out with alcohol, or just put on another coat. If you like what you read, feel free to sign up for my 'zine Wood Shop News (above the nav bar).
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Shellac dries hard and won’t yellow or darken with age. This makes it a great sealer beneath other finishes. I like to use it to keep pine pitch from bleeding through paint. It can also be used to help prevent blotching. Shellac hardens on top of the surface of the wood, making it is a good barrier for blocking impurities from seeping through a finish. It is extremely fast drying so you can build coats quickly.Shellac comes from the resin of the lac bug. The processed resin, called lac, is dissolved in alcohol to make the shellac that woodworkers use. Shellac is non-toxic and non-polluting. The denatured alcohol added to dissolve the shellac is toxic, so the usual precautions apply when finishing with shellac. However, once the shellac is dried the solvents evaporate and the shellac is again non-toxic.
