Originally Posted by
SMG
Acetone works OK with celluloid, but it does not give a full strength solvent weld. Nor, in my opinion does it disappear cracks as well as other chemicals. I use MEK on celluloid fountain pen repairs and it is much better than Acetone. There is another solvent which does give a full strength weld, but it is not available to the general public and is exceedingly toxic to use.
I have been repairing celluloid fountain pens for 6 years and have found that cracks welded with acetone are not as strong as MEK welded joints. I very strongly suggest against using any cyanoacrylates on celluloid as they just don't have the long term holding power of a good solvent weld. Also super glues are hygroscopic and will eventually fail when subjected to water (as razors often are).
The OP's suggestions are excellent, but I would rather wait at least 24 hours (a week is better) before working on any solvent welded joint. This ensures that all solvents are flashed out of the material and the weld has properly set.
Cheers,
Sean