Pyrocat-HD temperature compensation

[noseoil]

Does anyone have the numbers temperature compensation? My darkroom water temps are up to 80f now and may climb more due to humidity and the swamp cooler. I've been using 4% per f degree, but don't have a densitometer to prove the numbers. They seem to hold up, but with minimal agitation, times are getting short and I'm getting concerned. Thanks in advance, tim

P.S. for a short description of a swamp cooler, look here. Please, no comments about my tailor. Dead Link Removed

 

[wfe]

Can you cool it in the refrigerator down to 20C and avoid compensation? I also use distilled water for Pyrocat HD.

 

[Christopher Colley]

is Dead Link Removed this what you are looking for?

 

[Jim Noel]

I use the same time/temp compensation chart as for other developers. This may notbe exactly correct for pyrocatechin, but apparently it is close enough because my negatives show little or no difference from normal temperature.

I do keep the temperature below 82 degrees by diluting with cooled water.

Jim

 

[Justin Low]

I process my films at 30°C (86°F). I use a coefficient of 0.44 for times given for 20°C. I.e. starting time at 20°C is 12m; multiply 12 by 0.44, giving 5.28; I use a time of 5m15s.

This works well for me in most cases. I've tried cooling the solutions in the past, but our ambient temperatures make that an uphill task.

 

[m_liddell]

I've always used Ilfords chart here

You can probably also use:

New time = Old time × exp(-0.081 × (New temp °C - Old temp °C))
New time = Old time × exp(-0.045 × (New temp °F - Old temp °F))

 

[juan]

Tim, I use the same 4% figure with the Pyrocats. Seems to work for me, although I don't have a densitometer either.
juan

 

[sanking]

Tim, I use the same 4% figure with the Pyrocats. Seems to work for me, although I don't have a densitometer either.
juan

I use the same change of 4% per degree and it seems to work fine with Pyrocat-HD. But I always process between 70º - 80º F so don't know for sure what would happen going up to 85º-90ºF.

Sandy

 

[noseoil]

Thanks all for the input. Seems like the 4% answer is correct for most uses in summer heat. Just glad I'm using water out of the jug, not the tap. Tap water is now in the 90's here, so 80f is nice and cool.

I was getting concerned with minimal agitation and Efke 25 as I am under to 8 minutes with this technique at times, barely enough time to suite me. Thinking I may just double the exposure with these development times and sbr's, because as short as they are I'm concerned with shadow densities. They seem to be right on the edge now. tim

 

[juan]

I don't think I see the pronounced edge effects in my summer negatives that others describe with reduced agitation development. I think that's because of the short development time. I find that I have to use half the box speed of every film I've tried in order to get shadow detail - again, I think because of the relatively short development times.

juan

 

[john_s]

I've always used Ilfords chart here

You can probably also use:

New time = Old time × exp(-0.081 × (New temp °C - Old temp °C))
New time = Old time × exp(-0.045 × (New temp °F - Old temp °F))

In the absence of real data, the above formula is a very good method of interpolating and, to a degree, extrapolating to a different temperature. For what it's worth, I have calculated the coefficients that might be used instead of the above value of -0.081, based on the development times listed in Hutchings's "The Book of Pyro" for PMK, comparing times at 70°F and 80°F. I'm not saying that it is exactly appropriate for your film in Pyrocat-HD, but it might give some useful indication. For temp in °C, and in the range 70°F to 80°F

HP5+ Normal contrast: -0.087

T-Max100 Normal contrast: -0.052

These are the only films for which he gives times at two temperatures at normal contrast. These coefficients are for use with °C.

For °F use -0.0485 (HP5+) or -0.029 (T-Max100).