First, we mixed two drops of dye into 2 ounces of amber shellac, then applied three coats to a sample board with a rag dipped in the mixture, only to find the red cast was not as strong as desired. Then we repeated the mixture and application process using a four drops per 2-ounce mixture. That did it. After three coats, applied with the shop cloth, we had a red cast that mimicked antique walnut furniture.
Application is Key
When using tinted shellac or any shellac other than “clear,” a run or sag in your finish will show in the completed piece. The defect shows due to the color in the shellac being thicker at the run or sag. So pay close attention as you apply the finish.
There are three methods of applying finish. You can spray, apply the finish with a brush or simply use a clean shop cloth. Let the project size determine which method to use.
If the project is large, use a spray setup. This method allows the smoothest layering of shellac – provided you are accurate with a spray gun. Spray three coats of shellac. (Each coat must dry completely before adding the next layer.) Thin the shellac to a 1-1/2-pound cut. Store-bought, pre-mixed shellac is generally available in a 3-pound cut. To reduce the viscosity, mix the shellac in a 50/50 ratio with denatured alcohol. Thinner viscosity allows the shellac to atomize into finer particles, producing a smooth coat.
If spraying the mixture is not in the cards for you, by all means, resort to a brush. If you apply the shellac with a brush, it’s not necessary to thin the mixture. Apply the first coat making sure that you keep a wet edge and brush as little as possible, always brushing with the grain. If you attack this as most would in painting a house (a back-and-forth action), you’ll likely create more brush lines and a less-than-smooth finish.
No matter how you apply shellac, it might be necessary to sand between coats to remove nibs. And there is a caveat here. Sand lightly. Tinted shellac shows variations with differences in thickness and layers. If you cut through a layer of shellac to expose bare wood, you could change the look of the finish just as a run or sag does.
Because most of us brush on a thicker coat than we spray, apply a second brushed coat, then assess the color and film thickness. The color needs to be right and there should be a sufficient buildup of finish to achieve a smooth, even layer. If a third coat is needed, sand the second coat before adding another.
Apply shellac with a rag on small projects only. To keep the finish under control, thin the shellac mixture to a 2-pound cut. Adding one cup of alcohol into two cups of shellac does this. The thinner viscosity dries more quickly and reduces any gumming of the shellac. Keep the rag wet. If you experience “drag” (the cloth sticking to previously applied shellac), add shellac to the cloth. Use the same technique and precautions as suggested when brushing.
Knock Down the Sheen
As shellac builds the sheen also builds – the more coats, the higher the gloss. Of course you can leave the higher sheen as your finish, but a high shine, or glossy finish, amplifies any imperfections. A dull or a medium sheen is better. Rubbing out the finish with #0000 steel wool or applying a different topcoat will dull the sheen.
To achieve a satin finish with steel wool, you’re scratching the surface to no longer reflect light as much. This is a time-consuming step and the results are varied due to one’s ability to get tight into corners, and it’s possible to rub through the finish, again causing variations in the color.
Our choice for reducing the high shellac sheen to a satin or dull sheen is to add a layer of a different topcoat after one final sanding (this also helps level the finish). The resulting sheen is uniform over the entire piece. One caution: Confirm that your topcoat is compatible with the waxy properties of amber shellac. Some topcoats, polyurethane for example, don’t bond to wax.
If you are spraying your finish, a dull-rubbed effect lacquer is great. In addition, a wipe-on varnish is perfect for this step as well. Yes, each adds a small amount of yellowing, but that color increases the warming of the finish.
If you want to add a topcoat such as waterborne polyurethane (because it dries quickly and has a clear, non-yellowing appearance), apply a single coat of Zinsser’s Sealcoat, which is clear, de-waxed shellac. Then apply any dull-rubbed or satin topcoat.
This walnut finish met our requirements. Its two ingredients easily blended into one mixture, it can be sprayed, brushed or ragged on and the final color simulates the finish on antique walnut furniture. If you decide to rag-on the finish, I doubt that old leisure suit is an acceptable shop cloth – but that wide tie might just do the job. WM
Glen is a senior editor of Popular Woodworking.