If anyone can offer some advice it would be greatly appreciated.
I am an artist and I'm trying to make novelty boards. I take craft basswood and cut it into shapes, paint the wood with Behr flat black paint, and then use decoupage to glue my art prints onto the wood.
After waiting 24 hours for the paint and decoupage to dry, I brush on a thin coat of Minwax water based polyurethane. I coat one side and wait 3 hours before coating the back. I then let the wood sit for 3 days to dry. After 3 days the poly appears to be firm, shiny, and no figure prints appear in the finish. Everything looks good.....until....
I took the boards and put them inside small clear plastic bags to protect them. I had them sitting inside the house on the table for about 2 weeks. I pulled one of the boards out to look at it and the poly was marked up and dull where it made contact with the plastic. I checked the other boards and they all had the same problem.
I don't understand why that happened. I followed the directions and waited way longer than the recommended drying time. Is there a cost effective clear that I can brush onto the boards? I just need something to stay firm to protect the wood and artwork, offer some minimal UV protection, and survive sitting in a plastic package. My goal was to eventually sell these, but I can't now.
I chose brush method because I didn't like the texture that spray cans made. I don't want to sand if I don't have to. Brush strokes are OK.
Thank you in advance.