
Originally Posted by
Simon Barden
You want them to go on to a flat surface, so if there are any lumps or bumps in that area, then definitely sand them. A light rub with fine sandpaper will give more surface area for the decal glue to hold on to, but you'll need to then apply some poly over the top. I'd wait a day before applying the decals after this current coat, and then at most a day afterwards before the next coat of poly unless you lightly sand all the finish down again to give the new poly a key to grip onto if the original poly is now too hard to melt easily when the new coat is applied.