Chemical component exhaustion?

[MikeSeb]

I recently mixed up a batch of Mytol from my stock of the component chemicals. They are perhaps 18 months old and have been kept tightly capped in a cool (~68-72F) basement in their original plastic packages from The Photographers' Formulary. It's been 6 -9 months since I last opened them (life has gotten in the way of photography alas!)

My results, using times/temps (in Jobo) previously successful, indicate underdevelopment. I'm fairly certain that I mixed things up correctly.

Assuming I didn't screw up the mixing or the processing, should I suspect that the chemicals have gone bad? How would I verify this, short of wasting more film? What sort of shelf life should I expect from ascorbic acid, phenidone, and the other ingredients?

Suggestions appreciated, with apologies if this is a painfully stupid question.

 

[Jim Noel]

One of the more likely chemicals to lose potency is the developing agent, or agents.
The first thing I do when I receive an order of metol, phenidone, hydroquinone or any other developing agent is to move it from the plastic container which all suppliers now seem to use, to glass. Even the best plastics do admit oxygen over time and this oxidizes the chemicals rendering them weaker. There are other chemicals which I keep only in glass, but these are the most important.

 

[Tom Hoskinson]

I recently mixed up a batch of Mytol from my stock of the component chemicals. They are perhaps 18 months old and have been kept tightly capped in a cool (~68-72F) basement in their original plastic packages from The Photographers' Formulary. It's been 6 -9 months since I last opened them (life has gotten in the way of photography alas!)

My results, using times/temps (in Jobo) previously successful, indicate underdevelopment. I'm fairly certain that I mixed things up correctly.

Assuming I didn't screw up the mixing or the processing, should I suspect that the chemicals have gone bad? How would I verify this, short of wasting more film? What sort of shelf life should I expect from ascorbic acid, phenidone, and the other ingredients?

Suggestions appreciated, with apologies if this is a painfully stupid question.

See Jordan's Article on mixing Instant Mytol as an organic concentrate. Speaking from experience, that solves the shelf life problem.

(there was a url link here which no longer exists)