Pyrocat HD component expiry?

M

mpirie

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Does anyone have a note of the effects of exhausted constituent chemicals for Pyrocat HD?

The reason for asking is that the last 2 batches of PHD that i've made up have produced very low contrast negs compared to other batches i've made before.

Could this be a result of expired Catechol/Phenidone or others?

Mike
 
I was wondering as well about this because I have some old chemicals to make up Pyro 510. One of the constituents is Vitamin C, given the low price of this ingredient I might treat myself to fresh vitamin C and use the rest of the old chemicals.
 
I think one of the Pyrocat ingredients will absorb moisture out of the air over time if it’s not stored tightly sealed, which means if you’re weighing it out based on anhydrous weight then you’ll end up with less of it than you should have in the mix. Maybe something like that has happened?
 
Dave_P said:
I think one of the Pyrocat ingredients will absorb moisture out of the air over time if it’s not stored tightly sealed, which means if you’re weighing it out based on anhydrous weight then you’ll end up with less of it than you should have in the mix. Maybe something like that has happened?
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Thanks Dave.

I think that's the Catechol that you're referring to.

I have another supply of all components, but wondered if there was a way of identifying the failed chemical based on the resulting image.

Mike
 
Dave_P said:
I think one of the Pyrocat ingredients will absorb moisture out of the air over time if it’s not stored tightly sealed, which means if you’re weighing it out based on anhydrous weight then you’ll end up with less of it than you should have in the mix. Maybe something like that has happened?
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Sodium Metabisulphite might absorb a little moisture over time, but that should have no significant effect.effect.

If the Pyrocatechin has oxidised you will see a greenish colour, quite dark if significantly oxidised, There have been reports elsewhere of Phenidone problems, I've been using Phenidone since the mid 1970s with no problems. It may depend on where the Phenidone has come from.

The Metabisulphite is in Part A to ensure there's no oxidation during storage, if you increase it by 1.5 to 2X you will improve shelf life, it's still at such a low level to have no effect when the developer is diluted.

Ian
 
Thanks Ian.

The Pyrocatechin itself is brown and turns cherry red once added to the distilled water.

I normally mix part A in Glycol to keep the shelf life, but this time used distilled water.

Mike
 
Have you used the batch of Pyrocetechin before? That colour change sounds odd. I've been mixing Pyrocat HD for 20 years now never seen anything like that.

Ian
 
Yep, same batch that i've used for the last 2 years with no problem.

I have another 250g tub of the stuff, but don't want to throw out the remaining 200g if it's not the cause of the problem.

Mike
 
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