[Alt-photo] DAS (was Re: Luis Nadeau)

Joseph Smigiel smieglitz at gmail.com
Thu Oct 26 00:16:46 UTC 2017

Thanks Kees.

May I inquire further why you found DAS unsuitable for gum printing but not carbon or casein? FWIW, I became a vegan a couple years ago and will not be doing casein printing so I am looking for a safer alternative for gum printing. I also had planned on using exposed, unpigmented, dichromated, gum as a sizing in place of gelatin but would prefer a safer alternative for that purpose too.

Any further information on your gum printing tests would be greatly appreciated.


p.s., I'm finding conflicting (M)SDS sheets on the substance. One manufacturer (Sigma-Aldrich) indicates it is "not a hazardous substance or mixture" while others (TCI, Spectrum) characterize it as much more hazardous.

On Oct 25, 2017, at 4:13 PM, Kees Brandenburg wrote:

> Hi Joe,
> 4,4'-Diazidostilbene-2,2'-disulfonic acid sodium salt (DAS) is a good replacement for dichromate in carbon and casein, but not for gum. At least in my testing.
> It’s CAS Number is 2718-90-3
> Kees
>> On 25 okt. 2017, at 21:58, Joseph Smigiel via Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org> wrote:
>> IIRC, a couple years ago someone on the list suggested using a
>> diazo-stilbene (?) compound as a substitute for the dichromates in gum
>> printing. Did anyone on the list experiment with that compound? Results?
>> Joe

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