Quote Originally Posted by olleorama View Post
Getting ready with the industrial marker...
Sanford "Uni-Paint" markers:

Solvent-based, pigment (paint) markers. Sticks to glass, metal, plastic, etc.
Permanent on many surfaces. Durable on most.
Opaque & available in many colors: Red, White, Black, Yellow, etc.

I keep several in the darkroom, specifically for marking containers of things like my chems just for the reason you state. Many other markings, even Sharpie, sometimes come off. They usually come off at the least convenient time.

(Enter, Capt. Murphy. Stage left. )