Reply To: Devitrification, any fix after the fact?
I use whatever cold-work tooling that is appropriate, if the pieces are large enough to handle. So far I have a pneumatic wet grinder, and I also use emery paper from home depot, as well as a regular dry belt sander. A sand blaster and a wet belt grinder is on my Christmas list for NEXT year (this year I bought a house with a detached studio for Christmas).
Devit can be very severe if you have some cheap glass with questionable origins, so I try to cap those with a reliable clear thin (or a dusting of clear frit). I am surprised at hearing people fix it rather than removing it and doing a fire polish (or cold work polish). Obviously if you have questionable glass, you should do a compatibility test to confirm you can mix your clear with it successfully.
And yes, dirty glass can appear as devit. Even residues that will disappear completely in firing can leave residue marks. Things like stickers or sharpie ink on the glass and even tape residues will leave marks if not cleaned off first.