View Full Version : Do powdered chemicals go bad?
Will powdered Kodak chemicals like Dektol, Fixer go bad if it sits around for a long time in the bags? I have an opportunity to get a case of each for next to nothing from a school, But they dont know how old it is. Worth a shot?
They should be ok as long as no air has got into the bags. The easiest way to find out is to use some on a test roll.
The only real issue I can recall of dry chemistry going bad was with the 1ltr mix of XTOL (it was prone to going off within weeks of manufacture), which is why Kodak only ship it in 5ltr sizes now. Other than that you should be ok.
Thank you, I figure at $10 for 2 cases I might give it a go.
Chemicals go bad for four reasons.
1/ reaction with oxygen (should be minor since the bags are sealed)
2/ reaction with water (see 1)
3/ reaction with other chemical components (possible, but almost certainly minor)
4/ self-decomposition due to heat (depends greatly on the storage conditions and how much oxygen and water was in the bag when it was sealed)
I would assume 5 -10% decomposition and make the resulting solution that much more concentrated by adding 5-10% less water.
Depending on what and how many self-decomposition products are present, the storage life may be shorter than stated in the instructions.
Yes, they do go bad, but no-one has done any good research into how fast -- and it is quite likely that such research is impossible, because there are too many variables. This is why storage of powders is commonly given as 'indefinite'.
I would not try to make up the solutions at a higher concentration, but equally, I would adjust dev times until the negs print on grades 2-3 and I'd fix for 2x (min) 3x (max) clearing times. I'd be surprised if they didn't work. In the 60s I made up developers from raw chemicals dating from before WW2.
vBulletin® v3.6.8, Copyright ©2000-2018, Jelsoft Enterprises Ltd.