if you are talking about the stuff that CSUSA calls celluloid, I do not believe it is celluloid. In fact, read what I have below on Celluloid. i believe the stuff we use is nothing more than fancy acrylic.
From the Visconti Pens Website:
This material was invented by the Hyatt brothers in 1864 and is made from cotton, alcohol, camphor. The entire process to reach a workable material lasts from 4 to 8 months depending on the thickness. In fact the drying process is very important. Pens made in celluloid are made by two main process:
By Wrapping
Turned from a solid block
Both processes have advantages and disadvantages.
Wrapping : a 2/3 millimeters sheet celluloid is cut in long strips and rolled around a rod or pulled through a cone. The tube which is then obtained, is glued at the seam and dried for 20 days.
Advantages : Color is constant throughout the pen, no material is wasted.
Disadvantages : In some colors the seam can be visible.
Turned from solid rods : Advantages : Easy execution for all shapes possible.
Disadvantages : only a limited amount of patterns are available, 80% of material is wasted.
Properties of celluloid : Easy to color, allows many colors and designs. Its composition is totally anallergic, it partially absorbs humidity from the hands, so it feels smooth and comfortable. Shock absorbment (Technical : resilience) so it is an excellent material for pens.
Problems with celluloid : During manufacturing can be easy flammable and the process requires adequate precautions, it becomes soft at only 70 degrees. Constant exposure to light can cause abnormal drying and can becomes fragile! As in this case of some vintage pens.
Storage : Store in dark ventilated place at not more than 25/30 degrees.
Cleaning : Silicon sponge like those use to clean shoes