I'm having n auto body shop paint a Warmoth Strat body i bought new. It will be pearl white.

I put down grain filler and sanded it smooth. It sat for a couple of weeks before i gave it to the shop. Everything was fine.

The put on the white base coat and two pearl coats on yesterday. Everything looked fine.

Today the applied two clear coats, and the seam in the exact middle of the body lifted a tiny bit down near the bottom and and up the back about four or five inches. It's not a lot, but you can definitely see it.

They're going to try filling and sanding the area, then blending paint again.

Anybody have any idea what's at work here?
It might be due to the change in humidity or temperature between the location where you applied and smoothed the grain filler (your home, likely) to the shop performing the painting work. That causes the wood to expend or contract, and the glue line is supported by glue and will expand/contract differently.

That would be my guess.
There was three weeks between the time I did the grain filler and the body shop painting the guitar. I think it would have shifted by then.
you have to seal over the filler and body it up.
Last edited by ad_works at Apr 7, 2016,