Finishing Issues With Cyanoacrylate

Barry Irby asked: I made a chest of drawers that has four book matched burl panels in the top. The burl is black gum and light tan or blond and somewhat punky. There were some bug holes in it. I filled them with sawdust and thin cyanoacrylate glue. I now have circles round the holes that are darker. The chest will be lacquered. Will the discolorations disappear? Will the lacquer darken the wood just as the CA did? Would it be a good idea to soak each panel thoroughly and completely with CA? That might even out the color and toughen the wood, making a better top.

Russ Fairfield replied: Wicking of the CA into the surrounding wood is always a problem. It may not be as bad as it looks. Sometimes these areas will disappear under a finish. Sand and finish a test area and see what happens.

A uniform finish requires uniform penetration of the finish into the wood. The CA seals the wood grain and there will be no penetration of the finish into the wood. There are really only two ways to get uniform penetration of the finish when we use CA glues on a wood surface—sand until the CA disappears, or cover the entire surface with CA.

Sanding may be the better option because coating a large surface with CA is more difficult than it sounds. There will always be a line on larger surfaces, where the wet application has to meet a hardened surface. This line will always have a different thickness of CA than the surrounding wood, and it will always be visible. Sometimes the little spots can be the lesser of the evils.

We use CA glue to fill holes and cracks because it is faster, not better. There are several way to prevent the wicking. Famowood or WoodPatch is the best solution. It dries quickly, sands easily, and gets hardened with the finish. A filler made from the finish of choice or a wood glue and sanding dust or other filler material is still a good way to fill holes.

Another is to fill small holes with shoe polish wax. The wax fills the holes, gives them color, and the finish seals in. We can use gold Rub-N-Buff here, and give the wood a little sparkle.

If we insist on using CA because it is faster, we can seal the wood with the finish before filling the holes. On bare wood, a medium or thick CA would be a better choice because it doesn't wick into the surrounding wood as much as the thin.