From: John Cremati (johnjohnc@core.com)
Date: 01/12/02-02:31:20 PM Z
I have played around with some silk screening and I would imagine
you can buy the Diazo thru just about any silk screen supplier .. The diazio
I have used stains your hands where you almost have to wear it off to get
rid of it . A major silkscreen chemical manufacturer would be "
Ulano " Tel: 718.622.5200. You may request a test sample and they might
send it to you at no charge.... It has been a good while since I have bought
any thing from them so I hope it is still a good phone number and their
selling direct policies might have also changed..
My major question would be that the diazo may react differently with
the colloid thru a negative than the Dichromate .. It might not react
proportionally with the amount of light it receives as in carbon
printing...and I have no idea what you would use to bleach out the stain as
all I have ever tried was soap and water in the silk screening... I Good
Luck, I would be interested in how it turns out..John Cremati .
.. ----- Original Message -----
From: "robert" <robert@RobertSchaller.net>
To: <alt-photo-process-l@skyway.usask.ca>
Sent: Saturday, January 12, 2002 2:58 PM
Subject: Dichromate and diazo
> on 1/12/02 9:42 AM, BobWicks@aol.com at BobWicks@aol.com wrote:
>
> > Dave:
> > Diazo salts is the most recent application to replace bichromate that I
have
> > heard of. I do think the light sensitivity is slower. It is currently
being
> > used in the silk screen industry and it reacts in the same manner that
> > bichromates do on amino acid chains. As you may know bichromated salts
make
> > any organic material sensitive to light. Where the light strikes the
> > emulsion, amino acid chains are formed and they are insoluble. Diazo
works
> > in the same way but is safe to use and to the best of my knowledge it is
not
> > toxic (so the companies say).
> >
> > Bob
>
> Dear Bob,
>
> Thanks. This is certainly intriguing. It raises two groups of questions
> for me: which diazo salts, exactly, and where would one get them? And
how
> about the gum part -- how much, what exposures, etc.? That is, if anyone
> has done it and is willing to share.
>
> Secondly, that dichromate (or diazo) works by cross-liking amino groups on
> exposure to light answers a fundamental question about the mechanism
> involved. Is there a good source anyone could recommend for this chemical
> information? And also, exactly which frequencies of light are most
> effective for either substance?
>
> Robert Schaller
>
>
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