Some time ago, I was researching something (the first thing to go is your mind) when a revelation hit me, “wow they produce pens using all kinds of weird stuff.” I started taking notes, found websites providing generic dictionary-style explanations, and well that wasn’t going to work.
As I am not a chemist if I misspeak, my apologies, and please feel free to correct me. Also, if by chance you manufacture your own pens, feel free to comment.
I came across this quote and burst out laughing. I knew then I had to learn more.
“Casein doesn’t burn well but a celluloid pen in flames is memorable.” Deb @ goodwriterspens.com
Thermosets vs Thermoplastics: Thermoset is a material that creates bonds between polymer strands forming a tangled grid when heated that cannot be remolded or reheated after the initial forming. While thermoplastics can be reheated, remolded, and cooled repeatedly without causing any chemical changes.
Bakelite. It is not often used for pens due to its brittleness. It is the first plastic made from synthetic components via the condensation reaction of phenol with formaldehyde (thermosets).
Celluloid (trade names Permanite, Stonite, Pyralin). The first widely-manufactured synthetic plastic combining cellulose nitrate with camphor and alcohol. It replaced ebonite in the late 1920s. It can be made in virtually any color or pattern, and is easy to machine, yet slow to produce and is flammable. As celluloid ages, the camphor molecules are ‘squeezed’ out causing deterioration generally known as “celluloid rot.” Celluloid was replaced by cheap plastics in the 1940s. Celluloid acetate is not celluloid.
Casein aka Galalith (trade names Casolith, Lactoloid, Aladdinite). A milk-derived plastic, susceptible to moisture. Derived from 80% of the phosphoproteins in cow’s milk. It is rarely seen in American pen production but is more commonly used in the UK and Europe. It is a synthetic plastic material produced by the interaction of casein and formaldehyde.
Photo credit: Crimshaw.com
Ebonite (hard rubber or vulcanite). Early naturally-derived plastic is made by vulcanizing latex rubber with a large proportion of sulfur (25% to 80%) and linseed oil. Used to manufacture fountain pens until the late 1920s, thereafter primarily used to produce pen feeds and sections. The origin of the name reflects its intended use as an artificial substitute for ebony wood (thermosets).
Plastic. A generalization referring to celluloid, resin, and acrylic. Excludes hard rubber even though hard rubber is technically plastic.
Resin (aka Acrylonitrile Butadiene Styrene or ABS). A fancy modern name for plastic (honestly how else can one justify sales prices for a “plastic pen”). Resin actually undergoes a chemical reaction in the mold and cures from a liquid into a solid (thermosets).
Acrylic Resin (trade names Lucite or Perspex). Parker 51s is acrylic resin. It is typically derived from acrylic acid, methacrylic acid, and butyl acrylate, and/or methyl methacrylate. In the case of acrylic, the material is melted and poured into the mold to cool (thermoplastics).
How can I tell what my pen is made of?
Firstly, you must have an idea of your pen’s age, then as a general rule, pens predating 1925 are usually made of hard rubber, casein, transparent bakelite, or celluloid. Multicolored pearlescence or translucent pens are typically celluloid, as are most streamlined pens. Postwar, most penmakers transitioned from celluloid to cellulose acetate and injection-moldable polymer plastics (thermoplastics).
Hard rubber is easily identified by its distinctive smell (like a tire). Wet a celluloid pen and it gives off a distinctive smell (odor of camphor – honestly I have no idea what camphor smells like). You can also, test for celluloid by removing a tiny, tissue-thin shaving from the inside of the cap or barrel. Place the shaving on a glass slide, then add a drop of acetone. If the shaving is celluloid, it will dissolve; if casein, bakelite, or acrylic nothing will happen.
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