The Talking Machine Forum — For All Antique Phonographs & Recordings

Some time ago I picked a Phonycord Flexible record made in Germany. It is warped, want to flatten it, and don't want to mess it up. Don't know what material it's made of, it's red and transparent.

Search the board for posts about flattening warped records.

I would certainly avoid any applied heat with Phonycord discs. The thin celluloid layer can be a bit delicate.
The safest way would be pressing the record for a couple of months in a stack of regular 78s or other plain and heavy items. This has always worked out for me.