Casein aka Galalith (from Latin caseus, “cheese”) is a milk-derived plastic, susceptible to moisture. A synthetic plastic derived from 80% of the phosphoproteins in cow’s milk, and formaldehyde. It is rarely seen in American pen production; however, it is more commonly found in UK pens.
Identifying casein can be done by appearance and smell; rather than camphor, casein smells like antler, horn, or ivory, or vaguely like scorched hair. It appears more dull than celluloid and the curing process creates wavy striations. Alternatively, try the feel and color test. Is the pen a Conway Stewart model, highly colored and has an irregular colorful pattern? If the answer is yes to all these, it could well be casein. Hold the pen in your hand, does it feel warm to the touch? Yes – chances are it is casein.
Casein has been described as “the most beautiful of plastics.” It takes a wide variety of colors including delicate pastel shades, pearls, and mottles, and can imitate tortoiseshell and horn.
Do’s and Don’ts
Never, ever, never soak a casein fountain pen in water to remove ink stains or dried ink. Casein will expand by about 10% and become very soft losing its shape in as little as 2 hours = damaged beyond repair.
In his memoir, Walter A. Sheaffer recounts how Sheaffer once produced a line of colored casein pens which proved quite popular until the Midwestern summer caused the casein to swell and the sections fell out. The heat was identified as the cause. But I’m willing to bet the high humidity was most likely the cause.
Casein does not seem to be the ideal material to make fountain pens but it does produce BEAutiful pens. How about these three?


Conway Stewart is the manufacturer most often associated with casein pens. They only recently (by 2010) shuttered their casein pen production. Their remaining casein pen blanks were sold off to independent pen manufacturers.

Make you own
There are people who make their own pens. Some do this for fun, while for others it is a vocation. Both invest in equipment and supplies. I have found casein “blanks” as well as casein look-a-like blanks for pen manufacturing.

Some of the Conway Stewart casein blanks are absolutely stunning. The point is if you make pens, you can use this material (I would really enjoy owning a casein pen – just saying).
Casein is a “compressed form of the primary protein from milk,” what should the DIY pen guys consider when working with this material? I found a very informative thread on the International Association of Penturners (IAP) website, which I will summarize.

- Working with casein is not always the easiest, it is not very strong.
- At all times keep the material cool, use a spray bottle of cool water with each step.
- Do not drill or turn at high speed – use a slow speed.
- Use sharp carbide tools.
- Slow-speed sanding or the casein will burn (turn brown) and smell like burnt milk!
- The most important word of advice… be patient…take your time.
If you have small kids and enjoy home science projects, welp, I have a project for you. Make your own casein.
Owning a casein pen comes with responsibilities. As an owner, it is imperative you gain an appreciation for the qualities that make this pen unique. I do not own one but one day I will find a Conway Stewart casein pen that wins me over.
If you own one please chime in, I’d love to learn of your experiences.
————————-Reference——————-
- Pentrace: The History of Casein Use In Writing Equipment. Part 2
- Vintage Pens: Casein Pens: Most Aren’t
- Nationwide Plastics: What Is Casein Plastic?