I just want to pass along a trick I learned from a full size aircraft mechanic about patching dope. He was showing me a repaired spot on a Bellanca Viking, and said that he would tell the customer to bring the AC back in 6 months for a final sanding and rub out. Since dope continues to dry and shrink for quite some time, if he sanded it out too soon, the patch would reappear as the dope shrank. Let your patch dry for several weeks befor you try to blend in in again.