[alt-photo] Re: DAS - group buy
marekmatusz at hotmail.com
Tue Jan 22 15:55:43 GMT 2013
DO you have the email to Chris H. I would like to buy some.
> From: workshops at polychrome.nl
> Date: Mon, 21 Jan 2013 21:45:03 +0100
> To: alt-photo-process-list at lists.altphotolist.org
> Subject: [alt-photo] DAS - group buy
> Chris Holmquist or "holmburgers" at APUG is organizing a group buy of DAS. DAS is the acronym for 4,4'-Diazidostilbene-2,2'-disulfonic acid, disodium salt, tetrahydrate
> DAS is a non toxic replacement for dichromates and was also the sensitizer in the legendary Ultrastable pigment papers. I have been working with DAS for almost two years now and am very happy with the results. My first batch I bought at my local chemical supplier in the Netherlands and a second 1kg order directly from a Shanghai manufacturer in China. This group buy comes from a relatively old batch from Secant in the US. It has been stored refridgerated at Secant and was tested and approved by Tod Gangler of http://www.colorcarbonprint.com/. The prize is very competitive!
> DAS can be incorporated in the carbon pigment paper and has no dark effect. This speeds up working considerably as the pigment paper is presensitized allready.
> I have tested the chemical with several other colloïds. It does not work with Gum arabic. With caseïn though it is a perfect match. Also with some synthetic colloids results are very good. With casein exposure times can be cut down considerably, same with the synthetic colloïds.
> This group buy might be a nice occasion to do some testing. A good starting dilution is 3%. For carbon a Gelatin/DAS ratio of 0.06 is a good starting point. This means that for 1 liter 10% gelatin one needs 6 grams DAS.
> Kees | zerochrome.org (coming soon)
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