Acoustic Guitar Construction

I used a vacuum clamp for gluing on a couple of bridges, and each time I did, the footprint of the clamp left an impression on the finish that was difficult to rub out.

Has anyone else had that problem, or know of a way to mitigate it?

Your parameters -- finish, timing, method etc.?

I use the LMI clamp it on almost all the guitars I make and I use a home made one on ukuleles. I used mostly EM6000 or Shellac as a top coat. I had contaminates on the foam gasket once that left a mark. Otherwise no problems.