Polyurethane Over Varnish Finish. Improper techniques can lead to your paint finish to fail; Varnish and polyurethane are two popular finishes used for furniture refinishing today. Some varnishes may even contain polyurethane.
Myths about polyurethane are a good example of the problem.
Mark, 2 component poly cant be over 1 comp varnish , now there is regular 1 part polyurethane and this one is compatible with regular varnish so far i've gotten reasonable results using the inexpensive cabot spar varnish from lowes or home depot for interior finishing. It is important to understand when to use this kind. I have tried nail polish remover, orange pumice cleaner, dish soap, and a rough sponge. Do your research on finishes. This finish goes on clear, but ages into a nuance of amber and may yellow over time. They are very similar and some people even use the varnish is typically a glossy finish, but flattening agents can be added. The selection of a protective clear finish for your woodworking project is critical to the look and durability of your handiwork. It's common alkyd varnish made with some polyurethane resin added.