When the paper is wet the gelatin expands separating the silver bits, when it dries they get closer together so they look darker- next time you put prints on the drying rack take note of the gaps between the prints. You'll notice prints that were close to overlapping are quite a bit farther apart when dry. It's possible that different kinds of emulsion mixes ( chloro vs. flouro? )reacted differently as different "color"(warm/cold) black and white emulsions have different silver grain sizes. I found that the papers with the most variation in print size from wet to dry were the ones suffering most from drydown.
Ansel Adams kept a microwave oven in his darkroom to quick dry test prints to check the drydown effect and Fred Picker developed a timer which allows you to subtract a percentage of exposure time to compensate for the effect. If I remember my old printing habits correctly (original 1970/80s) Oriental Seagull required 3% decrease in exposure and Ilford papers of similar vintage required a 6% reduction to match the wet print. It's pretty easy to dial it in with a few experiments - it's hard to develop the trust that the print that looks a hair too light in the darkroom will look fine when it's dry.
Don't cook food in the same microwave oven if you choose that route. On Dec 1, 2009, at 5:35 PM, Roustom Family wrote:
Is the dry back effect of fiber prints something to do with how a sheet look wet vs. dry, or is there more to it than that?Is there a chemical process ongoing until the sheet is fully dry? Elias= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = ====================================================================== To unsubscribe from this list, go to www.freelists.org and logon to your account (the same e-mail address and password you set-up when you subscribed,) and unsubscribe from there.
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