U of S | Mailing List Archive | alt-photo-process-l | Re: another 3 layer gum attempt

Re: another 3 layer gum attempt

Well, I guess it depends on how technical you want to get. I determined an exposure using the Stouffer strips and then used that for ChartThrob, and that's worked well enough. Gum has enough wiggle room in it that you can be a little flexible in the calibration.

On Jul 21, 2009, at 11:21 PM, Paul Viapiano wrote:

I have a Stouffer 21-step tablet, and I understand how you can evaluate the emulsion from it, but how will that translate when making your digital negative without a densitometer? Shouldn't I use a (uncurved) step-tablet generated from my printer to find my exposure time?

Should I just use ChartThrob to make my wedge , find my time, print and have a curve generated...?

Man, I thought I had all this stuff down after going through it for pd printing...


----- Original Message ----- From: "Joseph Smigiel" <jsmigiel@net- link.net>
To: <alt-photo-process-l@usask.ca>
Sent: Tuesday, July 21, 2009 9:22 PM
Subject: Re: another 3 layer gum attempt


IIRC, my sun exposures for gum prints through a normal negative that
would print on #2 silver gelatin enlarging papers generally ran from
45 seconds to 90 seconds depending on the pigment, concentration and
dichromate salt. 3 1/2 minutes seems very excessive to me for
exposure to direct sun.

One printing typically resulted in maybe 6 steps on a stepwedge or an
approximate density range of about .90 from first to last visibly
different steps. A DR of 2.0 is way too much for gum to handle in
one printing.

A cheap Stouffer 21-step density tablet would probably get you to the
correct exposure determination very quickly and efficiently. It's a
good investment, especially if you are also doing other processes
like Pt/Pd.


On Jul 21, 2009, at 11:46 PM, Paul Viapiano wrote:

Hmmm...ok, I see that. I just brushed some out of my pigment/gum mix and can see that it should be a bright sunny yellow, of course.

For my testing I was using info on your site, re exposure, but I think I'm not understanding it correctly. You say that you should expose the test strip for the max amount of steps remaining after development, and I keep pushing exposure to move tone up the wedge, which I can see is wrong. But...hmm. In your reply, you mention using a fairly contrasty neg at under a minute in the sun...dang! I was originally using my digi-palladium negs which are approx DR 2.0 or slightly higher at 2 1/2 minutes, but the results were light, light, light ( http://www.flickr.com/photos/ viapiano/3718825618/) with little contrast...so this is the stuff that stumps me.


----- Original Message ----- From: "Katharine Thayer" <kthayer@pacifier.com>
To: <alt-photo-process-l@usask.ca>
Sent: Tuesday, July 21, 2009 7:53 PM
Subject: Re: another 3 layer gum attempt

Wow, if that's cadmium yellow light, then it's way overexposed; I've
never seen a pale yellow do that before. Caveat: I haven't worked
with cadmiums much except for test prints, as I find them too opaque
for my taste, but it didn't do that on the test prints I made with
it. I'd say try cutting the exposure in half. My sun exposures with
a black (fairly contrasty) negative tend to be under a minute.

I agree that it's more likely overexposure than staining; that
doesn't look like stain to me.


On Jul 21, 2009, at 7:31 PM, Paul Viapiano wrote:

Much thanks Joseph and Katharine...!!!

I'll study your replies and reflect on what I need to do next.

Pigment is WN Cad Yellow Pale - PY 35
Concentration is 1 gram pigment to 9ml gum
Using .75ml of that mixture to 1ml potassium dichromate (for a 4x5 print)
Sun exposure for 3 1/2 minutes
Clearing 20-25 minutes
Fabriano EW unsized for this first layer

I can print white highlights unsized. I've done it in other prints, so I think it's overexposure, not staining.

Your advice at least gives me a better grounding of what I need to look for, etc and is so-o-o very helpful!


----- Original Message ----- From: "Joseph Smigiel" <jsmigiel@net- link.net>
To: <alt-photo-process-l@usask.ca>
Sent: Tuesday, July 21, 2009 7:14 PM
Subject: Re: another 3 layer gum attempt


I would say your exposure is way too long or you have severe staining
going on, or a combination of the two. I'm basing this on the sort
of burnt mustard color of the border and some parts of the image, and
the fact that even the bright highlight on the nose has printed with
considerable density (or is heavily stained). That area should print
paper white or very close to it. Something (overexposure, staining)
has turned the highlights into midtones. I suspect the negative will
print OK though it seems a bit on the contrasty side to me.

What is your pigment, concentration, exposure, etc.


On Jul 21, 2009, at 9:23 PM, Paul Viapiano wrote:

Ha!! I needed to laugh...believe me...

Here is a combination of photo-negative-print that I was working on today. Trying to dial in my negative, exposure, etc...you know the drill.

What I would love is some feedback at this point, as I feel I'm flying blind after trying several tricolor gums that always turn out too light. I've made some adjustments to the neg, etc and here is what I have right now.


The neg is Blue (printing Yellow)...please feel free to comment on the density of the neg, the "look" of the Yellow print, or anything else that catches your eye. Am I on the right track or does somethng look terribly wrong here? I mean, I really don't know what the yellow layer should look like re: contrast, density...

Much thanks in advance for your observations...now back to the Scotch!


----- Original Message ----- From: "Katharine Thayer" <kthayer@pacifier.com>
To: <alt-photo-process-l@usask.ca>
Sent: Tuesday, July 21, 2009 5:17 PM
Subject: Re: another 3 layer gum attempt

This is what the Everclear is for.

On Jul 21, 2009, at 5:05 PM, Marek Matusz wrote:

The suggested order would be
1. Procure the bottle of whatever liquor
2. Start drinking
3. Expose test wedge
4. Keep developing your gum test and keep drinking
5. When the bottle is finished you should examine test prin
6. All of the sudden it will all be clear, even if for a brief moment

> Date: Tue, 21 Jul 2009 17:27:42 -0600
> From: kerik@kerik.com
> Subject: RE: another 3 layer gum attempt
> To: alt-photo-process-l@usask.ca
> Just don't drink the dichromate.
> I recommend Lagavullin.
> Kerik
> > -----Original Message-----
> > From: Paul Viapiano [mailto:viapiano@pacbell.net]
> > Sent: Tuesday, July 21, 2009 3:37 PM
> > To: alt-photo-process-l@usask.ca
> > Subject: Re: another 3 layer gum attempt
> >
> > (light bulb!! ding!)
> >
> > ok, ok...I have finally come to the realization that gum will
> > drive you to drink!
> >
> >
> > Paul
> >

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