U of S | Mailing List Archive | alt-photo-process-l | Re: Gum Calibration 2 (How to read color samples?)

Re: Gum Calibration 2 (How to read color samples?)

3. Test by calibrating each individual color first and then print them (as
21-step tablets) on top of each other (hoping to get a neutral result in
each step) later, inspect and dilute more (proportionally, trying to
balance any shift from neutral - if present) until black is convincing
black, middle gray is middle gray and highlights are highlights

Hi Loris,

I think you need to go a little further with your analysis. You should also remember the ORDER of printing each layer and that the curve for the first colour laid down will have a different curve to the second; and the third yet another curve than the previous two. My reasoning is that the first layer is on paper only, the second on paper + varying amounts of pigment/gum and again for the third layer. Also, if you are going to modify your solution strength after you have designed your curve then you will have to re-design the curve again using the new solution strength otherwise exposure and development will be messed up.


David H