Even if you aren’t a professional woodworker, you probably get called on now and then to look at finish damage on cabinets or furniture belonging to friends and neighbors. Your woodworking skills are appreciated in our mass-production society, and your friends and neighbors may not recognize that repairing a finish is not the same as making something out of wood. But it would be nice if you could help them out anyway.
The most common damage to a finish is missing color in minor nicks or scratches. Here’s an explanation of what to look for and how to go about repairing it. (I’m not going to discuss how to fill deep scratches or gouges; that involves a different and more complicated procedure.)
The Four Types of Damage
There are four categories of damage, each requiring a different repair procedure.
• Enough color remains in the wood, either from the natural color of the wood itself or from some remaining stain, so that all you have to do is apply a clear finish to the damage to blend it in.
• Not enough color remains in the wood, so you have to add some color to repair it.
• The wood is still sealed, and this prevents added coloring from penetrating. You have to apply a colored finish on top.
• The fibers of the wood are so damaged, that any liquid you apply makes the color too dark. You have to use a neutral-colored paste wax, water-based finish or a very fast-drying finish.
Determine the Problem
Because the fix for each situation is different, you need to test in advance to learn what is most likely to work. Here’s the easy test. Apply some clear liquid to the damage and see what happens. Does the liquid bring out the color already there to make the mark disappear? Does the liquid darken the damage, but not enough? Does the liquid do nothing? Or does the liquid make the damaged area too dark?
The best liquid to use is mineral spirits (paint thinner) because it will simultaneously show the color and remove any wax that might be partially sealing the wood. But mineral spirits isn’t always handy, and you don’t want to have to run home to get some. So here’s the easy trick, the method I almost always use to provide the clue.
Take some liquid from your mouth and dab it onto the damaged area using your finger. You could call this “The Spit Test,” but doing so might not endear you to your onlookers. “Liquid from my mouth” is how I describe it.
Whatever the liquid, and whatever the application tool, the liquid will tell you the situation within a couple of seconds. The color in the damaged area will blend, it will darken but not enough, it won’t change, or it will become too dark.
Here is how to proceed once you know what you’re up against.