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?)

25 Ekim 2008, Cumartesi, 1:39 pm tarihinde, davidhatton@totalise.co.uk
> 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.

I think that would be overkill and also almost impossible to do correctly
-> since if in case of balancing according a gray gradation (which means
that amnt. of pigment/gum in the former layers remains always the same),
you may not be on the safe side when printing the same colors in the same
order over VARYING amnts. of pigment/gum... Besides, since I have managed
to make beautiful and satisfactory (to me) tricolors by using a generic
curve (devised from printings by moderate concentration of paynes gray), I
don't see a point in digging so deep... I'm just looking for fine-tuning +
 repeatability based on firm grounds of calibration.

You're correct about recalibrating if paint concentration changes -> on
the other hand doing otherwise would be in contradiction of the concept
(and will) of calibration anyway...