PMK - A few questions

After a long hiatus, I have returned to using PMK. Since I live in the desert where it's warm most of the year, I keep most of my chemistry in a small fridge at 50F. When I went to develop some film this morning, I noticed that my Part B had crystallized a bit on the bottom and somewhat on the sides of the glass bottle. To wit,

1) Can I warm the Part B up some and get the crystals to go back into solution? Will it still be usable, if successful?

2) How warm can both Part A and Part B be stored and still remain viable? (My indoor ambient temp, during the summer months, runs about 79F.)

Thank you for any insight provided.

Alan

Alan9940 said:

After a long hiatus, I have returned to using PMK. Since I live in the desert where it's warm most of the year, I keep most of my chemistry in a small fridge at 50F. When I went to develop some film this morning, I noticed that my Part B had crystallized a bit on the bottom and somewhat on the sides of the glass bottle. To wit,

1) Can I warm the Part B up some and get the crystals to go back into solution? Will it still be usable, if successful?

2) How warm can both Part A and Part B be stored and still remain viable? (My indoor ambient temp, during the summer months, runs about 79F.)

Thank you for any insight provided.
Alan

Click to expand...

Allan..

May I suggest that you change over to Pyricat HD.. I did.. and its now the only film developer now''allowed in my darkroom.
I buy the ingredients and mix my own... I found it to be 'superior'.. not much in the way of 'stain.. a bit finer grain and a little 'sharper' a Check out Dr, Sandy King's tomes/curves etc. on his website.

Ken

Part B of PMK is just sodium metaborate, which should have an indefinite life in solution. Just make sure that it redissolves and everything should be fine. Now, considering the very small amount of actual developer solution used compared to water, you're not gaining much by refrigerating it. Water temperature is far more important to get close to development temperature.

EDIT: If you're worried about the shelf life of the solutions, I'd have to say that 79f (~26°C) is fairly low and it shouldn't be a problem. On the other hand, if part A doesn't crystalise in the fridge, then it would be ok to be kept in a fridge. Part B should be left outside.

KenS said:

Allan..

May I suggest that you change over to Pyricat HD.. I did.. and its now the only film developer now''allowed in my darkroom.
I buy the ingredients and mix my own... I found it to be 'superior'.. not much in the way of 'stain.. a bit finer grain and a little 'sharper' a Check out Dr, Sandy King's tomes/curves etc. on his website.

Ken

Click to expand...

Ken,

Thanks for the reply.

I've used Pyrocat-HD for about the last 10 years, but I'm growing weary of it dying on me suddenly; it's happened 3x. OK, I will admit that 3 times over all that time ain't much, but it's frustrating nonetheless! So, I figured that since I started using PMK (have Gordon's book, too) waaay back when, I'd give it another go and see how I fair with it. I haven't given up on Pyrocat, though. I still have a small batch that I mixed recently (which I feel I can trust) and I plan to do some comparisons of the same scene.

@Anon Ymous

Thanks for your input. I haven't noticed any issue with Part A so that one is probably okay in the fridge. I will keep the Part B in my darkroom, as you suggest. If I did store Part A at room temp (remember 79F), how long would it last?

I have started using Pyrocat HC in Glycol in a Jobo processor. I understand that it has a longer shelf life.

Moderators, can we have a pyro subsection added to the B&W developers forum section?

Alan9940 said:

@Anon Ymous

Thanks for your input. I haven't noticed any issue with Part A so that one is probably okay in the fridge. I will keep the Part B in my darkroom, as you suggest. If I did store Part A at room temp (remember 79F), how long would it last?

Click to expand...

I honestly don't know, but this temperature isn't really high. And while it's not the same thing, a Pyrocat HD part A solution I had mixed in water worked perfectly after two years and it was stored in atrocious conditions, exceeding 100f in the summer. In other words, don't panic and just do a clip test if you're worried.

Sirius Glass said:

I have started using Pyrocat HC in Glycol in a Jobo processor. I understand that it has a longer shelf life.

Moderators, can we have a pyro subsection added to the B&W developers forum section?

Click to expand...

I've heard that, too, and plan to try it. Plus, it looks simpler to mix!

Sirius Glass said:

Moderators, can we have a pyro subsection added to the B&W developers forum section?

Click to expand...

+1

As Anon Ymous mentioned, the PMK part B is sodium metaborate in a saturated solution. In order to get so much metaborate into solution, distilled water is necessary and the temperature needs to be kept high enough. If heating your solution won't get most of the precipitated solids back into solution, an alternative would be to add an equal amount of distilled water to the solution you have left (e.g., if you have one liter, make it two liters, etc.) and then just use twice as much solution B when mixing the PMK working solution. You can just leave out the extra water from your starting volume.

The other alternative is to get some sodium metaborate and mix a fresh B solution. It's easy and non-toxic. Just make sure you use distilled (not de-ionized, etc.) water for the solution and start with the recommended temperature.

PMK part A may be fine in the fridge, but I've found that the biggest enemies are air in a partially-full bottle and contamination. I usually start with a 500ml bottle of part A and then transfer it to a 125ml bottle when I've used half of it. This, and keeping anything but a dedicated and always-freshly-well-rinsed syringe away from the solution seems to help a lot. PMK part A goes brown when it's bad, so it's easy to spot. I only have this happen with rather old solutions and when there's just a bit left in the bottle.

Best,

Doremus