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Perceptol developer and temps


suse

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Hi

 

I'm about to try my first batch of Ilford Perceptol with HP5 400. But I'm having real trouble, for some reason, understanding their time-temperature correction graph.

 

All the times given on the inside of the pack are for 20 degrees...and the compensation graph might as well have been written in Chinese for me.

 

Does anyone know what HP5 at 24 degrees would be? I can't find anywhere on the net that mentions it either, so any pointers would be great!

 

Sue

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Unless there is something really curly odd about perceptol, then straight off the published data, eleven minutes stock solution at 20C taken up to 24C is a bit over seven minutes.

 

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There are other places, but you can find all this here, The Massive Dev Chart: B/W Film Development Times, Processing Data with stock, 1+1, 1+2, 1+3. Kind of seems pretty robust and tolerant. You might want to do strips some time depending on the effect you are looking for.

 

Once you are down to seven minutes though, you probably want to use 1+1 so that your pour out time isnt quite so critical, and which is something like 15min/20C or 10:45/24C

 

Apologies if you way are past this and I have missed something.

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Hi Rob

 

No, that's wonderful, thanks a million Rob. :) Just for educational purposes - how are you reading the graph? I can't see how to start approaching the diagonal lines (and where have the red dots come from!?) ???

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For 1+1 start at 15minutes @ 20C, take a line up to 24C, and the new temp is somewhere close to 11minutes.

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Perceptol is going to react in another way on higher temperatures. By the way it's an ultra fine grain developer but you will loose sharpness (acutance) and film speed. Use HP5+ on E.I. (iso) 250.

If you want to develop on higher temps it's better to use another ultra fine grain developer like CG512 (also sold under Rollei Low Speed) on 24 degrees C. It's a reference developer designed by Uddo Raffay (512 attempt to complete the test, that's why the name) and this ultra fine grain developer will produce more sharpness than Perceptol. You will also have a loss of film speed with the HP5+ : E.I. 200. (13,5 Min.)

Here is the dev. table for CG512 (all temperatures on 24 degrees C.).

http://www.fotohuisrovo.nl/documentatie/CG-512%20ontwikkeltabel.pdf

 

Best regards,

 

Robert

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BTW the development times / performance / characteristics of Ilford Perceptol are the same as for Kodak Microdol-X. So search google for Microdol-X and you are set :?)

 

Also, here's another vote for using these developers in 1+1 dilution form. You don't lose any ISO speed and the results are still v.fine grain.

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