oh ok veneer on the back that's a bit strange Frank, 1 thing i will tell you and others if your doing a paint finish don't use timber mate for grain filler as it will swell and shrink back as it sucks up the reducer specially if your using rattle cans as they have a retarder in them, which make them idiot proof with shine but take longer to flash off giving it time to soak in to the timber mate and will give you headaches when its polishing time, there are a few things you can use better than that, something i did come across with Ashton guitars they paint on fiberglass resin and sand it back to only leave the grain filled. I am going to try it myself on a Strat i have here after i finish the one's i doing atm you guys know you don't need a grain filler on basswood, maple or any tight thin grain woods

are you thinking on yours the glue is the issue, if its just a thin veneer can you just grab the sander and sand it off or maybe squirt a bit of supa glue around (pre undercoat)where you think its going to chip off but i hear you mate spending the time to get things just right and some thing stupid buggers it up been there done that lol Ill folow this build to see if you get i sorted if you need any help just let me know 😁