Remove old varnish by first softening or heating old varnish coatings, and then scrape or sand away layers until new wood layers are exposed. Apply new varnish or lacquer coating to new wood layers.
If furniture is older, old varnish coatings are easier to remove and may only require sanding with sandpaper or an electric sander. If furniture is newer, apply a liquid varnish stripper to break down chemicals in the old varnish. Heating is another method to use for removing old varnish. Heat the top layer of old varnish with a heat gun at a distance to soften layers. After either heating or stripping, scrape away varnish layers with a putty knife and wipe with a cloth for smaller varnish debris.