[alt-photo] Re: casein+ alt to dichromate

[Michel Debar]

Congratulations. Well done Kees. Michel
On Jun 20, 2012 5:52 PM, "Kees Brandenburg" <workshops at polychrome.nl> wrote:

> I have been printing a lot of ferric carbon and also another
> non-dichromate (read: less toxic) method. Second one based on
> diazidostibene as the hardening agent. This was the magic potion used in
> the (legendary) ultrastable tissue.
> Both (ferric and diazidostilbene) make it possible to make presensitized
> tissue because of the absence of a dark effect.
>
> But today I tried the ferric casein method! I never had printed casein
> before but got inspired by the recent casein thread and Peter's post. And
> the results were amazingly good!
>
> This is what I did:
>
> I bought a package of cottage cheese and sqeezed it in a fold of tissue to
> let it loose it's liquid. The resulting still humid mass was 65 gr. I
> crumbled it and added 50ml household ammonia (<5%) and let it stand some
> hours. This was too much ammonia I think because the pH was way too high. I
> added 2 teaspoons of citric acid powder to lower it to pH 6 and helped with
> a mixer to make a nice smooth colloid.
>
> Then I took my allready available classic cyanotype A solution (20%) and
> measured it's pH which was around 4.5. I added 10 ml household ammonia to
> set the pH to 6.
>
> Then I took an equal part of this pH adjusted cyano A solution and the
> casein solution. From this mix I took 20ml and added 1gr. lampblack aquarel
> paint.
>
> This was coated on a gelating/glut sized piece of paper and dried. Coating
> is similar to gum.
> When dry I exposed it 7 min, my regular time for cyanotype which was an
> excellent guess.
> After exposure the print went in a 0,3% peroxide bath were some real magic
> happens!
>
> This is were things go wrong with ferric gum, because gum is much more
> soluble then casein. With gum the peroxide doesn't have the time to do it's
> work. With casein there is just enough time to let it finish the hardening
> just before the development starts. Very nice!
> Also development is very fast, after 3 minutes in the perioxide I
> transfered it to another water bath and moved the print a bit in the water
> for 5 minutes. Ready!
>
> This is by far the easiest ferric pigment printing technique, and maybe
> also the easiest gum/casein approach.
>
> Try it!
>
> Kees
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