Rubber drop Tank Dried fixer...or developer

[Tom Nutter]

I have come across some hard rubber drop-development tanks and one of them has a crusty residue adhered to its insides...I am assuming it is fixer...so far have tried boiling water and a scrub brush to remove it...marginal results...any other ideas?

[Newt_on_Swings]

try a bit of vinegar too. but sometimes rubber breaks down and naturally become brittle and can have a white residue. It has appears on various rubber camera bodies and lens hoods I have left too long in the closet.

[Tom Nutter]

...pretty sure it's not the rubber deteriorating......I tried some vinegar and it worked a little better...think I will fill it with a 1:1 vinegar-water solution and let it sit over night.

[Tom Nutter]

next day upate: The 1:1 vinegar and water seems to have worked...Thanks for the suggestion!!