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Old 13th July 2022, 10:09 PM
Stocky Stocky is offline
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Default Pyrocat Part B maybe a bit weak?

I have used Pyrocat-HD successfully for some years. After doing not much photography for a couple of years, I have had to do some testing of a film new to me, HP5+, as my old favourite Neopan400 is no more.

I had trouble getting the results I sought at the development times that I have got from the web. My understanding has been that potassium carbonate solution does not deteriorate. I mix it up as instructed, 750g to make 1L of Part_B. According to graphical data from a graph at engineeringtoolbox

https://www.engineeringtoolbox.com/d...on-d_1956.html

the Part_B should have a density of about 1.532 (best estimate from graph) but mine is about 1.439 which contains about 597g/L instead of 750g/L (also best estimate from graph).

My potassium carbonate came in a plastic lined paper sack and I have that in a plastic bucket with a lid (ex food container), not the most perfect container but not terrible either I would have thought. It's opened very infrequently.

My question is: could my potassium carbonate have absorbed enough atmospheric water to alter its concentration that much? It is a free flowing powder still.

I have done a test using 1.26 times the Part_B as I'm homing in on a suitable amount of development and I'm getting close, but still at times longer than usually recommended.
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Old 14th July 2022, 09:50 AM
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Bill Bill is offline
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Can’t help with the chemical aspect but I use Tanol which I think is a similar developer to Pyrocat-HD and I have found that I need to extend the times from those on the internet and the Tanol instructions for HP5 Plus. I have ended up with 15 minutes at 24 degrees C with agitation (2 inversions) every 30 seconds. For FP4 Plus I cut the time to 9 minutes with the same temperature and agitation regime. I darkroom print so cannot comment if you are scanning.
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Old 14th July 2022, 06:33 PM
Lostlabours Lostlabours is offline
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I use a lot of HP5 with Pyrocat HD at box speed unless the light is contrasty, 17mins 1+1 to 100 @ 20ºC inversion twice every minute except the first minute where I invert at 30 seconds as well.

Ian
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Old 15th July 2022, 11:19 PM
Stocky Stocky is offline
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Thanks Ian and Bill.

At least that gives me some confidence that I'm on the right track.
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