Even though there is internet chatter about removing wax with 3rd party products, mineral spirits or vinegar, none guarantee success. There is an old saying in the industry. "Once you wax, you cannot go back". Nothing adheres well to wax and even after cleaning, the wood grain can become contaminated. Wax can penetrate the wood, making future paint or stain finishes or touch-ups difficult or impossible.
The risk of a failure in re-coating over a wax finish is very high. Your best bet is to clean, strip, and sand, but even that is problematic. Here is what we recommend if you want to go ahead.
- Scrub with a solvent, such as mineral spirits, to break the wax barrier. Follow with several applications of Acetone applied with gray scotch bright pads to scrub the surface.
- Then strip the surface. You want to remove as much wax as possible before sanding to minimize the risk of driving the wax into the grain of the wood from the friction of sanding.
- Strippers that contain Methylyne Chloride like Zip Strip or Savograns are aggressive strippers but harsher. Gentler strippers are citrus or soy-based such as Citrus Strip or Soy Gel.
After cleaning, test the first coat of finish for adhesion. Rub a nickel across the surface or scrape the first coat lightly after 24 hours with a moderately sharp object such as a blunt standard table knife, not a sharp or serrated knife.
If you are finishing as a professional, NEVER guarantee a finish applied over wax. Here is a suggestion for your contracts:
We cannot warrant finishes over an existing piece of furniture. If products containing silicone (such as dusting sprays), oil soaps or waxes have been previously used on the piece, they may contaminate a new finish and prevent adhesion. In these situations, it is best to strip and sand the entire piece. Occasionally, a previous wax finish or silicone may be impossible to completely remove.
________ (Initials) I acknowledge that this piece has never been waxed/polished with a silicone-based dusting spray or cleaned with oil soaps.
________ (Initial) I have no knowledge of previous cleaning products used but realize they may have been applied by previous owners.