Dewaxed shellac is a great sealer to put down on bare wood before applying your final top coat. It also serves as an effective intermediary coat between two finishes that are not otherwise compatible with each other, such as polyurethane and lacquer. Oftentimes people will ask whether normal shellac (not dewaxed) can serve the same purpose. Elisha “The Pneumatic Addict” performs an experiment in this video to show the different ways lacquer will adhere to dewaxed shellac and regular shellac.
To prepare for the tests, Elisha does the following:
Apply dewaxed shellac and normal shellac to a sample board. The two products are applied side by side onto the same board, which eliminates any variable that might be attributed to wood species, sanding preparation, contaminants that might be present on the wood, other finishes that might have been applied to the wood, etc. The shellac can be applied using whatever finishing technique you are most comfortable with, such as spraying, brushing, or even wiping.
Apply lacquer. Elisha sprays a nice even coat of rattle-can lacquer across the two samples. The finish is then left alone for a period of time to allow it to dry, so that the results can be more easily observed. If you want to repeat this experiment in your shop, you can use whichever lacquer product you prefer, as the results will likely be the same
The results of Elisha’s experiment might surprise you, and hopefully will inform your decision that next time you need to apply a seal coat of shellac onto your project. Let us know if you were surprised by the results of Elisha’s experiment, or if you have ever experienced incompatibility between finishes on your own projects.