[Alt-photo] DAS (was Re: Luis Nadeau)
jorj at jorj.org
Thu Oct 26 01:12:43 UTC 2017
DAS doesn't harden gum. It hardens casein and gelatin fine, although there are some issues with staining that have to be addressed (and can be addressed, in my experience).
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> On Oct 25, 2017, at 20:16, Joseph Smigiel via Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org> wrote:
> 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
>>> 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?
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