Paraphrased from the Ilford MG IV fact sheet: Ilford variable contrast
paper has three emulsions. All three are sensitive to blue light.
Differing amounts of green sensitizing dye are added to two of the
emulsions. All three have the same speed in blue light - the effect is
of high contrast due to the additive effect of three emulsions with
the same speed and contrast. When the paper is exposed to green light,
only the parts of the emulsion with the larger amounts of green
sensitizing dye react initially. The image is of low contrast because
of the differing sensitivity to green light of the three emulsions.
By the way, thank you all for your informative responses to my request
for info.
Earl Johnson
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Received on Thu Mar 18 16:12:25 2004
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