Very nice! I like the Casein very much.
Nothing but positive input here, Alex.
Questions come to mind though. Do you paint the tubes? Does casein need a finish? If so, what? Lastly, how durable as a pen is casein?
TIA,
Cav, when I made one, I was worried about the Casein being too translucent if it got thin. I was worried about nothing. Even to a very thin diameter, it is very opaque. You will see "shadows" behind it, if you get it really thin - which is true of any material, but even then it's pretty much a solid color that will not require painted tubes.
For finishing I avoided wet sanding, or wet polishes, and just polished it to a high luster with MM and Berea's Mirlon Total stuff. There again, I think I may have been worried about nothing. Casein is made from milk proteins and is kind of like bone. It is water soluble and you could theoretically dissolve it if you left it in water long enough (years, probably) or if you boiled it down like making a bone broth or bone glue. But a little water for a few seconds probably doesn't hurt. I'm not sure though that a wet polish would make it any shinier.
Also, being quite permeable, it can stain easily. A colored wet polish like Novus Two might change the color. A white polish like Novus Three or Ultragloss might be okay. It's possible Casein could be ideal for a material you could paint on.
BTW, if you use CA to glue your tubes, be aware that its ability to retain moisture in the air makes CA glue set up almost instantly. I had to drill out a tube that set up one third of the way out. I couldn't budge it. I recommend white Gorilla or Sumo Glue.
I am presently using one as a carry along. I keep it in a pouch and so far it has been very durable, and stayed clean.
This piccie shows a Conway Stewart (Ivory) Casein. Note the cool, radial end structure, and the threading, which Casein seems durable enough to handle.
