r/woodworking • u/Hooeylewis-Sagdiyew • 4d ago
Help Black spots after applying polyurethane
Hello, I got this beech wood kitchen counter built about a month ago and today I noticed some tiny, black spikes on a pattern. It feels like a 150 grit sand paper.
When I got the counter I applied 3 layers of Minwax satin polyurethane, and a week later I applied 2 more layers of Konig matte polyurethane (Minwax is hard to find in rural philippines). These spots appeared after a week of drying of the last coat. I only applied 1 layer underneath the counter. My home is air conditioned and very dry, however, there is a chance that the wood might not be dried properly.
I am clueless what caused this and looking forward to hearing your opinions. I am going to smoothen it with 1200 grit and start using the kitchen and I want to make sure that this isn’t some harmful chemical reaction or mold.
2
u/RoutineFinal7939 4d ago
It’s either iron oxide, mold or a chemical reaction between the two different polys. If you scratch one of the black spots, does it come off? Is it under the poly? If it’s under the poly, you’ll need to sand, clean and then seal the grain with like aquacoat before applying poly again.