Nobody ever knew how to make stable celluloid......Stable celluloid is in fact an oxymoron.I love vintage celluloid knives, but I'm always aware that celluloid can go at any time and store my cell knives accordingly to minimize collateral damage to my other knives. I stay clear of any celluloid knives made after the 1940s, especially those made in the 1980s through the early 2000s. The celluloid manufacturers seem to have forgotten how to make stable celluloid.