When a wood finish starts to alligator all is not lost. You may be able to re-amalgamate the finish. Amalgamation is combining two or more things into one form. Re-amalgamation is the process returning a finish that has separated due to heat or moisture into a unified finish. Re-amalgamating an old finish can be a long process. There are no guarantee’s that the wood underneath is not damaged. The first step is to determine the type of finish you are using. Find and inconspicuous location on the piece, take a small amount of denatured alcohol and apply, if it gets sticky after about 30 seconds, you have a shellac finish. If it is not sticky take a small amount of lacquer thinner and apply it piece. If it is sticky you have a lacquer finish. If it is not sticky try mixing the alcohol and lacquer thinner and then reapply, if that doesn’t work your piece is probably varnished, you may be able to sand away some of the damage and apply an overcoat, but for now we are going to deal with shellac and lacquer.
The process is the same for re-amalgamating shellac and lacquer the only difference is the solvent used. It’s important to work fast and concentrate on a small area at a time. Use a natural bristle brush and apply the solvent with the grain. The finish will dry quickly, if you see a mistake, wait to fix it on the next application. Some pieces are only mildly damaged and will re-amalgamate after 3 or 4 applications, other pieces will take more applications. Tape the areas that you are not working on to prevent runs. Remove hardware when possible for a uniform application. Pigment and finish tends to concentrate along the edges, when it dries it leaves an uneven look. That can be corrected later in the process. I sand and then clean with mineral spirits between coats. It’s what you do when applying finish for the first time and it’s a good habit to get into. I use a 220 paper to start and gradually use finer and finer paper, finishing with 8000 grit paper. If needed you can mix a small amount of shellac and alcohol, or lacquer and lacquer thinner in a glass jar for the final coats.
Re-amalgamation isn’t for the feint of heart but it can renew a piece of furniture. At the furniture Barn Kyle and I are re-amalgamating an 1890′s acanthus carved Berkey Gay mahogany dresser. Stop in to the furniture barn to see our progress!