Perceptol and its effects on film speed
I had thrown in a question in the Tr-X and Perceptol 1+3 thread and got a couple of answers which caused me to do a bit of research and has prompted me to start another thread. Otherwise my post ends up hijacking another thread unfairly.
Briefly for those who may not have seen my post, I asked whether there was a "chemistry" explanation for the fact that the fine grain developer, Perceptol, which seems to have a characteristic of producing a reduction in film speed of anything up to 1 stop should also be recommended for Ilford's fastest film D3200 and at full box speed. I have used it for D3200 and noted that it produced negs with much finer grain than ID11 which certainly improved print grain. So yes it does work well with D3200 in terms of taming grain and achieving box speed as Ilford claim
So far I have been offered a couple of explanations about an increase in speed being correlated with increased dilution but further research on the Ilford site seems to support this in some cases and not others.
To make things easier I have put films, both Ilford and non Ilford into two lists of Box Speed and Less Than Box Speed at stock; 1+1;1+3 dilutions as follows:
Box Speed Less Than Box Speed
D100 - all dilutions D400 @ 200 all dilutions
@ 320 1+1
D3200 - stock only HP5+ @ 250 stock
@ 320 1+1 & 1+3
Pan F -all dilutions APX 100 @50 stock only
FP4+ - all dilutions APX400 @320-all dilutions
SFX stock & 1+1 Plus X @64 all dilutions
TMax 100 all dilutions Tri-X @200 all dilutions
TMax 400 all dilutions
Acros -stock only
Neopan 400 all dilutions
There is no information on TMax 3200 or Neopan 1600 at all.
Some tentative conclusions:
Some 400s are OK at box speed and others not
One 3200( Ilford) is OK at box speed and others fast films Tmax and Neopan have no info. This may indicate that Ilford hasn't researched these with Perceptol or that it isn't recommended. However if a combo has been tried and isn't recommended then there is normally a comment to that effect.
Both 100 and 400 Tmax are fine at box speed as is Neopan 400 but Ilford's own D400 isn't.
Most of those that are OK at box speed are OK at all dilutions except D3200, SFX and Acros. The first and last are OK at stock and SFX is OK at 1+1
So there seems to be some contradictions here in terms of the more speed = more dilution. The best example being D3200 itself which you'd expect to be better at higher dilutions as it is very fast.
It could simply be that Ilford simply hasn't done all the research on Perceptol and all the film combos but you'd expect it to have info its own new 400 film, D400, at box speed, when it can supply it on its rivals TMax and Fuji Neopan 400? Otherwise Ilford users of D400 who require ISO400 might switch to rival brands.
Cabn anyone offer the equivalent of a "general theory" on Perceptol which reconciles the information I have unearthed?
AKA Confused of Daventry
forget about manufacturers tests and what they equate to, because they're unlikely to mean anything in the real world anyway. I think you're overcomplicating the whole business. Using the recommendations as a guide and seeing how it turns out, then adjusting your next film accordingly is probably the best approach to take.
I have used Microdal X 1:3 with Tmax 3200 shot at 1600 with excellent results. I only stopped used Microdal, and Xtol for that matter, when I could not longer get either in quart sizes. I think the massive development chart list times for Tmax at 1:3.
Paul, there's a "close-to" formula for MX in Anchell & Troop's "Film Dev. Cookbook". It works well and very easy to mix it yourself.
Thanks all so far.
Before I find out about reconciling my findings on Perceptol with some theories expressed and some apparent contradictions, I think I may need to find out more about the layout system governing an APUG post. I carefully separated the lists into films and dilutions with times for box speed and films and dilutions given at less than box speed. It was fairly clear as I had set it out while word processing it. I then I posted it and signed off, never thinking that it would be mangled as it was.
I have signed in tonight to see that my thread's layout wasn't transferred as I had set it out and now barely makes sense. This might help explain why there were few replies. I don't think I'd have replied myself on seeing it as it is but would have switched off, frustrated at trying to make sense of it. It has merged the two lists and looks confusing.
Just to clarify box speed times and dilutions applied to D100; D3200;PanF; FP4+;SFX; TMax100; TMax400; Acros and Neopan 400
Non box speed times applied to D400;HP5+; APX100;APX400; Plus X; and Tri-X.
There were no times for TMax 3200 or Neopan 1600
My observations set out after the mangled lists did at least transfer correctly but only make sense if the lists were correctly set out. So, sorry for making it more difficult to read than it should have been.
I simply wondered if there was an overriding explanation based on known chemistry that could reconcile what I'd found.
I am sure that those times and ISO/EI film ratings given by Ilford are a very good basis for development but on practical grounds as well as intellectual curiosity I wondered why Ilford have times for a rival's range of 400 film(TMaxand Fuji) at box speed but not their own(D400 and HP5+ or another former rival( Agfa APX100 or 400)
Maybe there is something that ties those non box speed films together and something else that ties the TMax ones together. Or it may simply be that Ilford haven't gotten around to doing a complete list of times.
It simply stuck out like a sore thumb that there were box speed times for Kodak and not for their own flagship D400. Some might conclude that Perceptol is better able to cater for box speeds in a rivals' film(Tmax and Fuji) than its own. A conclusion, I'd imagine, that Ilford marketing people men wouldn't like consumers to reach.
Maybe it's a question best asked directly of Ilford and equally maybe and more importantly, it exercises only a minority of APUGers of which I form the majority and otherwise holds little interest which I need to accept as a fact of life.
Finally on pure practical grounds what would be the "formula/rule of thumb" for converting, say, those 400 films for which times are given at EI 320to development times at box speed. I'd be particulary interested in running HP5+ and D400 at box speed and still developing in Perceptol.
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Tell him that there are no security risks with the PRE code and he may just enable it for us all.