Not much can be done about shrinking, but you may be able to flatten it out by warming it up and clamping between 2 pieces of wood.
Trick is that celluloid is pretty flammable. Safest way to go is to dunk in hot water (near boiling). Just don’t do it using a pan over a flame on a gas stove. Turn the heat source off first.
The thing with celluloid is that when it starts to warp it's on a downward spiral of decay and may start to outgass heavily which risks the well-being of the guitar to which is attached.
Another comment.
The thing with celluloid is that when it starts to warp it's on a downward spiral of decay and may start to outgass heavily which risks the well-being of the guitar to which is attached.
Is it possible to reshape a 1957 aristocrat pickguard?
This is exactly what I did with the pickguard on my 1956 Aristocrat. I had it clamped between wood for more than 6 month I believe and it is pretty flat now. However it was in a pretty good condition before, just warped upwards quite a bit. It wasn't shrunk in size.you may be able to flatten it out by warming it up and clamping between 2 pieces of wood. Trick is that celluloid is pretty flammable. Safest way to go is to dunk in hot water (near boiling).