Mixing dry pigments with shellac for minor colour repairs takes some practice and a fine artist's brush.

Minor scratches in the finish will be easier to repair if you scuff the surface of the finish first.

Fix small scratches in lacquer and shellac by painting in the proper finish with a small artist's brush. Then lay on a coat over the entire surface.

Scrapes, areas of finish and colour removed from edges, are generally easier to repair than scratches, which occur in the centre of a side or top and must be stripped and refinished. The first step is to determine if it's only the finish that's damaged or if part of the colour is gone, too. Wet the damaged area with naphtha. If the wet surface blends in with the rest of the finish, you only have to repair the finish.

If both colour and finish are missing, the naphtha will make the scrape appear lighter than the rest of the finish. In this case, you'll need to replace the original colour first, then apply finish. The easiest way to replace colour is to use a felt-tipped repair pen. The colour selection is limited, but you can apply several different colours to achieve a match. A more difficult method is to mix some dry pigment with shellac and paint it in with a fine artist's brush.

On a lightly scratched varnish or polyurethane finish that is thick enough, your best bet is to sand out any scratches first. I usually start with 600-grit paper, but I've occasionally used 400 grit. While the traditional method calls for wet-sanding, I prefer to dry-sand. Wet-sanding gives you a false illusion of finish thickness, and it's possible to go through the finish before you know it. Depending on how deep the scratches are, you may have to sand the entire area to avoid hollows created by working one area too aggressively. Smooth out the sanded finish with fine steel wool to blend it in. You can match any original sheen by rubbing it out with 0000 steel wool or by using rubbing compounds. If the scratch is deep and white, and the finish is varnish or water-based, you'll need to strip and refinish the entire surface if you want a perfect repair.

If a finish is too thin to sand out without going through, simply add more finish. With an evaporative finish, such as lacquer or shellac, some scratches will disappear and blend right in with the new finish, as long as they're not too deep. Fill the scratch with finish by applying some lacquer or shellac with a red sable artist's brush. Several applications with overnight drying may be needed. When the scratch has been filled, sand the built-up layers back to a level surface, then apply more finish to the entire area. When the finish is dry, rub it out to the sheen that you want.