U of S | Mailing List Archive | alt-photo-process-l | RE: muddy gum print--help?

RE: muddy gum print--help?

DO you mix the pigments for each print/layer? I found it most helpful to mix a stock solution to keep the consistency. I actually also measure the amount of emulsion for a given print size. This keeps my gum thickness constant and in the optimum range. There has been a few responces to your email already, but I would like to add some observations. It seems like you have the negative and exposure nailed, or close to it. I would venture that the pigment choice and pigment concentration is your problem. That was already mentioned. In my opinion ultramarine is a very wimpy blue (I know somebody will jump and say not at all, but...). The blue layer is most responsible for having dense shadows. Try indanthrone blue and you would be amazed at what a good blue does to your prints. Making stock solution also helps as several people on this list arrived at similar stock solution concentrations through independent experimentation of their own. And while gum allows for countless experimentation it helps a lot by starting with the best guess.
In terms of order of printing, IMO it  is mostly determined by the method of registering negative and opacity of pigments used. I register by visual aligment and have to print blue first. In the old days the only yellow available was a very opaque cadmium yellow and it would be printed first. You have a number of transparent yellows and magentas at your disposal and if you pick your pigments well, the order of printing is not that important.
As far as sizing paper I wrote a while back that I use gelatine dichromate with great success, no volatile organic material needed.
Keep us updated on your progress
> Date: Sun, 12 Apr 2009 12:32:06 -0700
> From: cryberg@comcast.net
> Subject: Re: Re: muddy gum print--help?
> To: alt-photo-process-l@usask.ca
> Folks:
> Thanks for your help. I'll reprint Monday (as I mentioned yesterday I
> stupidly ruined the example I posted).
> Does the order of printing matter? The example was Cyan, Magenta, Yellow.
> I can't size--asthma keeps me away from VOC's and my urban loft provides no
> back yard or garage with fan.
> I use Fabriano Artistico Hot Pressed--it seems to stain less than Arches.
> My Lukas Process Magenta (PG2) does stain, though not as much as some of
> the other magenta/reds I have tried. My Daniel Smith Hansa Yellow Medium
> (PY3) stains too. The Daniel Smith French Ultramarine (PB29) stains very
> little.
> I did a curve for each pigment at a concentration which seemed to me to be
> the most pigment I could use. Prints made with those concentrations and
> curves were even worse than the one I posted. Trial and error led me to
> pigment concentrations of about 70% of maximum and exposure time of about
> 80% of what I had determined “scientifically.” I suppose I could post the
> curves if you think it would be helpful. I use potassium dichromate on the
> cyan and magenta, ammonium on the yellow due to excessively long times with
> yellow and potassium.
> Exposure is BL tubes. Timer is GraLab. Registration pins by Pro Art
> (that's supposed to be a joke).
> Any help before I reprint (a better magenta? a different printing order?)
> would be welcomed.
> Any help after I reprint, of course will be also welcomed.
> Charles Portland, Oregon

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