pyrocat HD problems
I have read and participated in threads on several APUG regarding PC HD and film speeds/ dilutions etc and am finding some anomalies with my brew compared to the findings of others.
With my 1st lot of PC HD (dry chems weighed for me but put into solution by me) I have always used a partial-stand type method (1 min agitation then 10 inversions every 3 mins). I found the best ei was approx minus 2/3 stop for most films. this was a little under what most were experiencing but I was ok with that.
I have now realised that my 1st lot was infact too strong. I copied the chart from Sandy King's unblinking eye article and misread it ... I mixed chemicals for a 200ml stock solution into a 150 ml stock solution (DOH!) So this time, I have mixed the chems the same (I didnt find out the mistake until after the mix) but reduced the amounts I am using so instead of 1:1:100, i used 0.75:0.75:100 which would make it the same as if at normal strength (I hope). I have tested some FP4 and Delta 100 - both at manufacturers speed ratings.
Now I am back in the darkroom, I have been able to use my RH designs analyser pro in densitometer mode to check densities.. I am now getting a whole stop less of film speed in zone i densities (placing it at 0.10 above FB+F) and the zone viii densities show an increase of development time by about 4 mins to approx 16 mins (placed at 1.15 above FB+F) for condenser enlarging. This has confused me a bit.
Although I appreciate that individual methods will always cause differences, my questions are:
1. How does this compare to others results (am using roll film); and
2. what would the effect be if I increase the part b solution to about 0.75:1:100 or more? - is that likely to speed up development or EI? would there be any adverse effects with this (loss of edge effects or increase in grain?)
3. Would I be better using the 1:1:100 dilution that i was used to (this was never properly tested as I was scanning negs at the time) and running the test again?
thanks in advance - I'm just trying to save on film use as it looks like my favourite Ilford types wont be around for much longer!
Development time is greatly influenced by type of agitation as well as time and temperature. Because there are so many possibilities all of the BTZS type testing that I do is made with sheet film in tubes with slow rotary agitation at a temperature of 72║F to keep this variable as constant as possible. I don't generally do BTZS testing of roll films but empirical evidence suggests that given similar development in terms of time, temperature and type of agitation results will be closely comparable with both FP4_+ and HP5+ to what you get with sheet film.
Originally Posted by Leon
Questions to ask if you are not getting what appears to be full emulsion speed are,
1. Were the stock solutions mixed correctly, with exactly the right amount of each chemical? Pyrocat-HD is very well balanced to give maximum emulsion speed with very low B+F. Small inaccuracies in measurement, especially of the phenidone or of the bromide, could result in a developer of less energy than standard. For example, even a decrease of as little as 10% in the amount of bromide (used as the restrainer) in the stock solution will produce a significant difference in results.
2. How are you determining correct time of development for the type of agitation you are using? For minimal agitation I generally recommend an increase of about 35-50% over normal development time with standard agitation.
3. How confident are you in the accuracy of film exposures? I am highly suspicious of all field tests which claim to show a differnce in EFS between different developers because the margain of error of our equipment is often equal to or greater than the small differences in emulsion speed that could be expected.
It is difficult to pinpoint the specific reasons for higher or lower EFS with any developer when there are so many possible variable. However, in multiple tests over many years with FP4+, which is my standard film for comparison work of developers, I have always gotten slightly better emulsion speed using the 1:1:100 dilution of Pyrocat-HD than with either D76 1:1 or PMK 1:2:100. And I get almost the same EFS with Delta 100 in Pyrocat-HD 1:1:100, though I have not run comparison tests with it against other developers.
thanks for the reply Sandy, I carry out as controlled a test as I can using the same spot meter on a uniformly lit detail-less wall.
the chemicals are measured and supplied Mike Maunders from speedibews and I mix them into solution - my mixing is probably a little slapdash so that is probably one factor for me to consider ....
how about an increase in the b solution?
Originally Posted by Leon
Increasing the amount of B solution in the working, or increasing both the amount of A and B in the working, is almost certainly not going to result in an increase of real effective film speed. In fact, it may do the opposite as I have always gotten more real effective film speed with the 1:1:100 dilution (or 1:1:150 with extreme minimal agitation) than with stronger dilutions. However, doubling the amount of B, or doubling the amount of A or B, say with a 1:2:100 or 2:2:100 dilution, will definitely give a much more energetic developer that will develop film to a given density much faster.
Development times with Pyrocat-HD 1:1:100 should be shorter than with either D76 1:1 or PMK 1:2:100 for any given CI when conditions of develoment are similar. If they are not something is definitely not right, either with the stock soluition or with the working solution.