Being a big fan of Italian pens, I have often talked about the various pens I have acquired, noting which ones were resin or celluloid.
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.
It produces beautiful pens, but has it challenges in terms of a material to work with. The companies I have visited all showed how they store their celluloid rods in steel cabinets, or seperate buildings, outside the main factory. That is because it is so unstable. I can attest to the pronounced small of camphor from the rods.
The curing is the skill. If the celluloid is not cured correctly, the celluloid will continue to loose moisture and shrink. The pieces are places in trays in ovens and baked for very long periods of time, at low temperatures
When I visited with OMAS they explained the process in detail. It takes about 350+ days to make a celluloid pen.
Celluloid being baked in trays in the baking ovens.