December 2008

Monthly Archive

A Scale Test

Posted by on 07 Dec 2008 | Tagged as: Gum Bichromate

To get the hang of gum printing it may be a good idea to print tone scales with the intended pigments. This print will be a useful reference when choosing colors and determining exposures and tone rendering.

A digital step wedge was printed on transparency film and plain paper which was then oiled for translucency. These “negatives” were gum printed (with different exposures) on a sheet of Somerset paper, sensitized with gum emulsion containing ivory black pigment.

Another Gum Try

Posted by on 01 Dec 2008 | Tagged as: Gum Bichromate

Here is another try to achieve results similar to the previous gum test, using only three print layers.

Thought I should make another version of the negative. Here the correction curve makes it somewhat lower in contrast, compared to the previous one.

The first layer (left) and the second layer on top of it. Funny how warm ivory black looks on Somerset paper…

All three overlapping layers printed.

The Process

Three stock pigments were made and used diluted for the sensitizer:
1. Maimeri Ivory Black 1 g + gum arabic (14 Baume) 20 ml
2. Maimeri Prussian Blue 1 g + gum arabic 20 ml
3. Maimeri Alizarin Carmine 1 g + gum arabic 20 ml

Coating was made with a foam brush, then evened out with a Hake brush.
Paper was Somerset 200g, preshrinked.
Sizing: Gum + dichromate + water, 1+1+1 parts, exposed 4 min. with Osram Ultra-Vitalux from one meter, washed for 60 min.

Layer 1
Pigment: 1 part Ivory Black Stock + 1 part gum + 2 parts dichromate
Exposure: 18 min.
Development: 30 min.

Layer 2
Pigment: 1 part Prussian Blue Stock + 1 part gum + 2 parts dichromate
Exposure: 6 min.
Development: 70 min.

Layer 3
Pigment: 1,5 parts Alizarin Carmine Stock + 0,5 parts gum + 2 parts dichromate
Exposure: 10 min.
Development: 24 min.

Clearing: Potassium disulfite 5% 2 min.