Pyrocat HD question: Solid precipitate in Solution B?

[Robert Langham]

I've been working through an order of Pyrocat HD in Glycol. It's a wonderful developer, as many folks say. I noticed that my solution B bottle has precipitated out some kind of solid. When the bottle is shaken, it sounds like plastic pellets in the bottom. I didn't notice it until recently, (though I wasn't shaking the bottles before drawing the solution for use.) Doesn't seem to have effected the performance of the developer.

Anyone got an idea? I rather like this developer for HP5 Sheet film. I'd been using Xtol, which I liked a lot but I think I prefer the Pyrocat.

Thanks.

[sanking]

Sounds like some of the potassium carbonate fell out of solution due to low temperature. Place the bottle of Solution B in a warm water bath for a couple of hours and carbonate should go back into solution.

Sandy

[Robert Langham]

Sounds like a simple fix. Thanks!

[Harold_4074]

I would suggest redissolving the salts only if the bottle is nearly full. Crystallization occurred because the solution was close to saturation to begin with; if you have used a substantial amount of the Solution B, you have removed proportionately more water than carbonate (or whatever the salt is). Warming up the remaining solution may allow you to redissolve everything, but you will now be using a more concentrated solution than you did originally, and I don't know how sensitve Pyrocat is to alkali concentration. It will also drop out again if the temperature decreases.

I have the same issue with PMK, but I realized that if the darkroom stayed at approximately constant temperature, the saturated solution (with excess at the bottom of the bottle) would give consistent results anyway.

[sanking]

Correct, if a large percentage of Stock Solution B has already been used then warming the solution to redissolve the potassium carbonate will result in a slightly more concentrated solution. However, the original solution is so concentrated it probably won't make any difference in the working solution. The Stock B solution is a near saturated solution of potassium carbonate, and contains 750 grams of the chemical in one liter of stock solution. Yes, that is 750 grams of potassium carbonate in one liter!! I doubt that more than 5-10 grams of the chemical has dropped out of solution so warming it is not going to have much real impact on the working pH given the buffering ability of the carbonate at this concentration.

Sandy



"Crystallization occurred because the solution was close to saturation to begin with; if you have used a substantial amount of the Solution B, you have removed proportionately more water than carbonate (or whatever the salt is). Warming up the remaining solution may allow you to redissolve everything, but you will now be using a more concentrated solution than you did originally, and I don't know how sensitve Pyrocat is to alkali concentration. It will also drop out again if the temperature decreases."

[Robert Langham]

A little hot water and agitation drove it back into solution. Sounds like it will be fine but if there is any change it's a quick fix to order more. Next bottles I'll watch closer and follow the directions to shake it. Going to test some FP4 in it to be ready for shadowed wall shapes in Canyon de Chelly. Need a little more contrast than I was getting with HP5.

[HMG]

I have a similar situation. I was given some PMK, via an intermediary, from an experienced photographer who said it was good. There's a 1L bottle of solution B that is about 90% full and has what I estimate as about 1/8 to 1/4 cup of crystals in the bottom. Many of the crystals are large flakes, about 3/16" x 1/2".

Soaking for a few hours in hot water (with a couple of water changes to keep hot and periodic agitation) has not had a noticeable effect on the volume of crystals. As I shake, I see a lot of tiny grains, I assume the same precipitate.

Obviously I can try using it but, before I do, I thought I'd seek the collective knowledge of the forum:
- Is there another way to force it back into solution?
- If not, is this volume of precipitate likely to effect usage? I assume I should filter it out.

Thanks.

[Peter Gomena]

I think PMK uses a "kodalk" accelerator solution (I think it's sodium metaborate), not sure what the trick is to get it back into solution. Warm it and shake it for a while and see what happens. Pyrocat-HD solution B goes back into solution pretty readily, but it's a different animal than the PMK solution B.

[HMG]

I think PMK uses a "kodalk" accelerator solution (I think it's sodium metaborate), not sure what the trick is to get it back into solution. Warm it and shake it for a while and see what happens. Pyrocat-HD solution B goes back into solution pretty readily, but it's a different animal than the PMK solution B.

You are correct about the Kodalk. "Kodalk" is also on the handwritten solution B label. I should have mentioned that in my initial post.

[esearing]

Is there a temperature range Pyrocat HD in glycol should be kept at? My darkroom is in my garage and can go from 40 to 80 degrees over the course of a year.