Gum printing stain.

Darrin · Nov 28, 2019

Hi all!

I just made my first gum print with the photo formulary kit. Everything went well but I think I have that yellow stain. I did what the directions in the kit said but it’s still there. Is this an actual stain or just the yellow of the yellow watercolor? What do you guys do to get rid of it? Thanks!

Andrew O'Neill · Nov 28, 2019

Is that a tri colour gum?

Darrin · Nov 28, 2019

Yes it is.

Dan Pavel · Nov 28, 2019

It looks like the yellow color layer and not a general stain to me. I have never used the colors from the photo formulary kit but yellow proved to always be a difficult color. I have yet to find the best yellow for gum prints. I am now using Schmincke Horadam watercolors, some of the best watercolors out there, and the yellow layer still makes problems. I have computed correction curves for each color layer and while the cyan and magenta layers share the same curve the yellow one needs a different adjustment curve and exposure time. Probably it is related with the way yellow affects the response of the sensitiser to the UV light. However, yellow proved to need shorter exposure times than the other colors.
That's my experience. The experience of others may be different.

Dan Pavel · Nov 28, 2019

I develop gum prints for 30min. in darkness without agitation (changing the water each 10 min.) and after that I continue with the print face-up and agitating the water, in full light, for how long it's needed (no more than 15 min. usually). That helps to develop the print until the color looks right. Sometimes I make paper inkjet prints with only the layers I am developing to help me appreciate how the gum layers should look after development.

Aimee Danger · Nov 30, 2019

Darrin said:
Hi all!

I just made my first gum print with the photo formulary kit. Everything went well but I think I have that yellow stain. I did what the directions in the kit said but it’s still there. Is this an actual stain or just the yellow of the yellow watercolor? What do you guys do to get rid of it? Thanks!

Which order did you do the layers in? It looks like you did yellow last.

Darrin · Nov 30, 2019

I did yellow first, magenta and then I did blue last.

Aimee Danger · Nov 30, 2019

If there is bichromate left in your layer, the next layer won't adhere very well. I always develop each layer for 60 minutes upside-down with no agitation in 70º water just to be sure.
Also, if the gum is spread inconsistently or pigment/gum combo not stirred completely, you can get brighter patches of color after exposing and developing.

Darrin · Nov 30, 2019

Would bichromate being left on the layer cause “soft” images like this. This just has a yellow and magenta layer but it’s really soft.

Aimee Danger · Nov 30, 2019

Do you mean 'soft' like the gum is tacky or 'soft' like the image has a painterly, not precise look to it?

Darrin · Nov 30, 2019

Soft like the image looks faded and has little contrast. After adding a dark color like blue it helps but yellow and magenta in the image above have little contrast.

Aimee Danger · Nov 30, 2019

There are so many things that could be! If you think it's something in your process, check that: you used a curve on your digital negative that is specific for printing gum, you used premium glossy paper, high quality as the paper setting in your printer when you printed the negatives (there are other settings I can recommend but they're dependent on your printer), your contact printing method is a tight seal between your negative and paper, you used the emulsion side of your negative against the paper, you exposed soon after your paper was dry (i.e. you didn't coat the paper and then wait a few hours or days), and when you developed you didn't agitate the bath.
However, the gauzy, 'painterly', imprecise look is what gum is known for. Your picture above is small, but from what I can tell it's pretty consistent with most gum prints in its gauziness. It may just not be a look you like for your work. My work has always been high-contrast and high-drama, but I'm kind of using gum as a way to chill out a bit and explore a new way of looking at things.

Como · Dec 1, 2019

Most of the time there is a stain in my gum dichromates. Sometimes you can solve it by adding some layers with less gum and less pigment of the other colors. The exposure time needs to be longer.
For instance my first three layers are:
gum 8 ml, dichromate 8 ml, aquarell paint 0,8 gr, exposure time 1 minute
When there is a red stain I ad a blue and yellow layer with:
gum 6 ml, dichromate 8 ml, aquarell paint 0,4 gr, exposure time 2 min 30 sec.

The print here is made with a base blue layer in cyanotype and 8 layers of gum

Gum printing stain.

Darrin

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