Probably a combination of using a hard brittle Urethane put on too thick over a surface of a different softer flexible finish that wasn’t prepped correctly. Also went thru a few freeze thaw cycles that didn’t help.What caused all those cracks in the Urethane? Moisture?
Only if I have to. I spray 2 coats at a time with sanding in between with Abranet and a palm sander. Usually I put 10-12 coats on in a controlled spray booth. If the stock is raw wood I’ll brush and sand 5-6 coats first before spraying.I can’t wait to see it..... will you wet sand and buff it like a car too?