[pure-silver] Re: perceptol 1+1 and grain

  • From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
  • To: <pure-silver@xxxxxxxxxxxxx>
  • Date: Tue, 6 Nov 2007 13:42:57 -0800

----- Original Message ----- From: "Shannon Stoney" <shannonstoney@xxxxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Tuesday, November 06, 2007 8:19 AM
Subject: [pure-silver] perceptol 1+1 and grain

back to an old topic of about a week ago. I bought some perceptol today, but I suddenly realized that if you use it full strength it's pretty expensive! What about using it 1+1? Does that give you some fine grain qualities (although maybe not as good as straight)?


For a time I was using Microdol-X 1:1 by accident. It delivered pretty good results but the main virtue of Microdol and Perceptol are their extra-fine-grain properties. These are obtainable only when used at full strength. At 1:1 the grain is not as fine but film speed is somewhat greater. At 1:3 the film speed and grain is the same as with D-76 but the developer begins to show edge effects, that is it boosts acuatance. Acutance is a term invented by Kodak to mean the increase in apparent sharpness that accompanies the exageration in contrast at the edges of objects in the image. The eye interprets this as shapness even though the actual rendition of detail (resolution) is relatively poor. Because the scale of the effect is fixed it is of less importance for medium and large format negatives than it is for 35mm. If you want economy you might try re-using the developer or replenishing it. I am not sure if either Kodak or Ilford still makes a packaged replenisher. Re-use can be done if the development time is extended a little, however, there will be some change in shadow contrast from the accumulated reaction products. I find that most 35mm negatives do not have the smoothness of tone rendition of larger negatives. This is a hard quality to describe but is not hard to see. I find that I begin to get this smoothness when using an already very fine grain film, like 100T-Max with one of these developers. The MSDS for Microdol-X and Perceptol suggest they are identical. The fine grain agent appears to be sodium chloride (table salt) but some old Kodak patents suggest there may be some amine there also.

Richard Knoppow
Los Angeles, CA, USA
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