What is celluloid?

(And why is it not the same as cellulose nitrate/nitrocellulose?)

Celluloid is usually cited as the first synthetic plastic.  Its origins go back as far as the 1850s, but as a commercial product it is to be dated to the 1860s, with successful large-scale manufacture being more a development of the 1870s.  It was only in the 1920s, however, that fountain pen makers wholeheartedly embraced the material.  Unlike hard rubber, celluloid could be made in an almost unlimited range of colors and degrees of transparency, in patterns capable of simulating almost any natural material imaginable.  Although some cheap pens were made of molded celluloid, nearly all better pens were made of rod or plugged tube stock that was machined to shape.

The main ingredient of celluloid is nitrated cellulose, yet celluloid and cellulose nitrate (also known as nitrocellulose) are not the same.  To make celluloid, cellulose nitrate must be plasticized with camphor, celluloid's other essential component.

True celluloid is still being made, but much of the so-called celluloid on the market today is actually cellulose acetate, which has a decidedly different look and feel.