U of S | Mailing List Archive | alt-photo-process-l | Re: Printing gum with little pigment

Re: Printing gum with little pigment

Marek, I found one more set of strips that might or might not bear on this, but the sun is shining straight directly my eyes and I can't see the monitor, so I'll have to scan them later. I would say it doesn't bear on it very much, because the question I was addressing with these tests was what happens if you keep adding more pigment after you're already at an optimum pigment concentration to get a deeply saturated color and maximum number of steps for the pigment. This is quite different from your question, I think, which is whether a very small amount of pigment will yield more steps as well as (by definition) less DMax than a more pigmented mix. This comparison somewhat supports my supposition about an upside-down U-curve, because 2x and 3x the pigment show a slight dimunition in number of steps (1 step down in each case) from a more optimum mix (7 steps). And provides more support, although certainly none should be needed at this point, for the long established gum principle that the mix that will give you the deepest DMax will not give you the longest tonal scale. But as I said, that's different from the question you were asking; this is more at the other end of the scale. Pictures at 11 (or sometime later, at any rate).

On Jan 17, 2009, at 5:25 PM, Katharine Thayer wrote:

On Jan 16, 2009, at 3:05 PM, Marek Matusz wrote:

Here is where the argument breaks down. What you consider a weak/ moderate pigment I might be using and defining as strong. The only way for you to convince yourself of the validity of your assumption is to cut the pigment concentration in half or quarter and print something side by side. I am looking for people that have done it already and can share the actual prints/test strips.

Okay, this is all I found in an afternoon of searching through boxes of test strips and test prints, that would serve the purpose. It would have taken me less time to just go down and print some, but I don't want to go down there; it's cold. . :--) Anyway, here is a comparison of two Stouffer 21-step prints in Prussian at two different pigment concentrations; it is consistent with your observations. These would have been exposed and developed in a way to yield the optimal DMax and maximum number of steps for each mix, per the instructions on my site.


Hope that's useful,