Casein

[Loris Medici <mail@loris.medici.name>]

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,
Loris.