U of S | Mailing List Archive | alt-photo-process-l | Re: Casein -> it's the paint

Re: Casein -> it's the paint

I was out of home for fiyur days so I reply you only when you are near to th solution of your problems.
I printed in casein dichromate about two years ago (I have some prints in the Rodolfo Namias Group website, search for "Motherhood"), with the aim of acheving some single layer casein prints.
The dried casein+dichromate is hard to dissolve in plain water. You can use (like you did) some ammonia in the development water after the print washed off most of the dichromate in the first 10 minutes, or also some drops of hypochlorite. If the paper still won't spoil, try also with a garden sprayer from a distance on the vertical print out of the tray.
Casein print has a longer tonal scale than gum, and you can get stained highlights if you don't use sized paper. You will be able to put in the casein solution about ten times the amout normally used with gum.
As for the preparation of the alkaline casein solution, I have found useful (and harmless both for me and the casein) pouring 0.8 g of casein and 10 cc of 10% ammonia in a small (125 cc) glass jar with an hermetic lid (the type used for pickes and for sterilizing jams and peeled tomatoes). Then I heated the sealed jar in hot (60°C) water for about 15', swirling the solution from time to time. After this, I put it in the refrigerator.
The solution stinks, so it is better to have it cooled before opening the lid.
Hi all,
I tried with powdered pigment and this time (3rd trial) got an image. So,
(for the moment) I conclude that the reason of not getting an image in the
first try was the acrylic paint. The 2nd was made w/ the same emulsion but
this time by putting a little of ammonia in the development water (by
suggestion of a list member), it was better compared to the first time
(reacted to force development) but nothing near to usable / successful.
I'm making these tests on plain Yupo paper. And casein is much much better
in adhering to the paper -> in all my trials with gum on plain Yupo, the
emulsion had left the paper completely...
A side note: I got tonal reversal with the 3rd trial -> it was a very dark
/ contrasty mix exposed only 1 minute under UVBL (2 parts casein/pigment +
1 part 5% AD).

22 Mayıs 2009, Cuma, 10:06 pm tarihinde, Loris Medici yazmış:
I did my first casein trial yesterday evening, w/o any success. See below:
- 0.8g casein (Kremer's)
- 5ml tap water
- waited 10 minutes (to let casein absorb water - I'm not sure if that's
necessary but did so anyway, I was not in a hurry...)
- added 8 drops of 25% (910) ammonia (it seems to be a lot, will try
halving the amnt. next time)
- I mixed the slurry (cream consistency) until it looks homogeneous
- I added 5ml of 5% ammonium dichromate (it turned to yellow - because of
excess alkalinity I presume...)
- I mixed the solution (not a slurry anymore, pretty homogeneous looking
solution slightly less viscous than my usual gum coating mix)
- made up a coating solution by adding the dichromated casein solution to
a very small amnt. of W&N acrylic color (burnt umber)
- coated the paper, dried with a hair dryer, humidified the paper with an
ultrasonic humidifier, exposed for 2 mins. under a bank of UVBL tubes (I
didn't get a dichromate image after exposure)
- developed(!) face down for 20minutes
I got absolutely no development, no pigment coming off, no dissolution of
binder at all.
What could be the cause?
Overexposure? Using acrylics? (But I know someone - Guido Ceuppens - who
uses acrylic colors with casein...) Both? Any other thoughts?
Will try with only 30secs exposure tonight...
Regards & thanks in advance,