Pieces of celluloid in trays to be placed in the oven for drying.
I am not a chemist, but as it has been explained to me, celluloid is a vegetable derivative that is produced by combining cellulose with nitric acid and camphor.
The reulting material produces beautiful pens. But the material has challenges. I have visited many Italian pen companies. Typically, this includes being shown how they store the celluloid rods. Always in steel cabinets, and often in separate buildings. The raw celluloid is unstable. You can smell the camphor. There are cases where fires have broken out and almost destroyed the factory.
Celluloid has been around for a long time. The first patent was in 1870. In its natural state it has no colour. But by adding dyes and/or pigments the material becomes very attractive.
The material costs more than a resin, and the material takes time to cure. If the celluloid is not cured correctly, the celluloid will continue to loose moisture and shrink.
For proper curing I have seen how the pieces of celluloid are placed in trays, the trays places in ovens, and they are in essence baked for long periods of time at very low temperatures.
When I visited with the staff at OMAS they explained the process in detail. In the end, they explained it took about year to cut, cure, and then shape the pen parts to create the finale celluloid pen. If it is done right, then the celluloid if very strong and durable.
Why go to all this trouble? It is because of the detail and colours of the celluloid. Also, celluloid has a great feel in the hand.