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Glue Smears

Question

I discovered that I missed some glue smears after applying shellac to cherry. What corrective action can I take? – Ken Kuster

Answer

Bruce Hamilton replies: It has been my experience that the least intrusive way of dealing with these situations is to hide the defect with color. I would scuff sand the area with 400 grit paper to assure good adhesion and then use colors to match the surround area to blend the defect away.

We use dry fiasco colors like Mohawk and Behlens touchup powers or artist acrylic color form the local art store. Use a small brush and imitate the grain lines as well but remember the less color you use the better. You can always make touchups darker but you can’t make them lighter.

Seal the repair with a light coat of aerosol shellac. If you don’t get the right result the first time, a little alcohol will easily take it off. Don’t forget that hiding a defect with color pigment or dyes will affect the reflectivity of the wood grain to some degree but this is often hard for others to notice. You are the final judge however.
Al Breed replies: The only way to really get rid of the masking that the excess glue left is to remove the shellac at that spot and scrape the glue away. Otherwise the glue will slow the oxidation of the cherry (which will be dramatic in the first few years) and leave a light spot, especially if you’ve oiled the wood. Using animal glue and cleaning up with hot water almost eliminates this type of problem.

Marty Milkovits replies: Shellac is a very forgiving finish, making it easy to repair. The easiest and best way is to scrape and sand out the glue spot. Glue is harder than wood so start by taking a few light passes with the scraper and then sand the area exactly as you did the rest of the piece. Wetting the area with either water or mineral spirits afterwards should show if you got it all. I take extra care in finial sanding to look for glue spots because it is such a pain to fix them after the finish is on.

Bill Newbold replies: Therein lies the beauty of a shellac finish – it is relatively easy to repair at almost any stage of its life. I’m assuming you used ordinary carpenter’s glue and not the waterproof variety, in which case you could wipe the glue area with a cloth rung out in hot water. Keep rubbing until no glue is visible. If that fails, then rub a 50/50 mix of warm water and white vinegar. Now if that fails, then resort to a sharp card scraper and scrape off the glue. If you penetrate the shellac and you most likely will, then touch up the area with 220 garnet paper and apply a kiss coat of shellac.

If the piece is stained you may have to go over it again. Always apply a darker coat of stain to a patch, as a lighter color will stand out like a “wart”!

Tags: Finishing, Glue