Re: was Miracle size for gum now tonal range
Minor correction: in my perplexity I misread condition (2) although the misreading doesn't change or clear up anything. It's actually (3) that provides the pointless comparison, exposing the 2x dichromate the same as you would expose the 1x dichromate. (2) proposes to expose the 1x dichromate twice as long as you'd normally expose it, which also makes no sense to me, why you would do that. You'd just end up having to develop it twice as long to get the same final result.
So, to summarize, in case the point got lost somewhere: if the overall question is how should you compare two dichromate concentrations as to their effect on tonal scale, my answer would be just what I did for the demonstration on my website: you'd determine the correct exposure for each of the concentrations, using a step wedge, then you'd compare the number of steps printed for each of the concentrations at its proper exposure, using the same coating mix, same paper, everything else the same. As I reported in the earlier post, when I did that I found that at saturated dichromate concentration, at the correct exposure, the pigment mix printed 8 steps; at 1/5 dichromate concentration, at the correct exposure, the same pigment mix printed 4 steps. Hence my statement that more dichromate = more steps.
On Oct 11, 2009, at 12:04 PM, Katharine Thayer wrote: