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Re: applying images to ceramicsWARNING
----- Original Message -----
From: Sil Horwitz <silh@earthlink.net>
To: <alt-photo-process-l@skyway.usask.ca>
Sent: Friday, April 06, 2001 10:31 PM
Subject: Re: applying images to ceramicsWARNING
> Before you go on with your talk of doom and destruction, tell me: how
> much dichromate is left in the image after exposure and washing, before
> firing? I haven't made any studies, but I would surmise there isn't enough
> to register with ordinary qualitative analysis studies. I'll repeat: there
> should be no dichromate remaining after exposure and washing, no
measurable
> amount that could do any harm. The dichromate is merely a catalyst to
> reform the structure of the colloid so that it becomes insoluble when
> exposed - it does not become a part of the colloid (gum or gelatin)
molecules.
>
>
> Sil Horwitz, FPSA
> Technical Editor, PSA Journal
> teched@psa-photo.org
> silh@earthlink.net
> Visit http://www.psa-photo.org/
> Personal page: http://home.earthlink.net/~silh/ >>>>>>>>>>>>>>>>
Sil,
Thank goodness there is one man out there who knows what he is talking
about. Are you and I the only ones who have deduced that the orange colour
that appears in warm water when a gum print is washed is infact amm/pot
dichromate???????
Did Demachy never mention this???!! ...No, probably not - being French.
Seriously though - the only problem with printing gum on ceramic is the
possibility of the pigment colours degrading in the heat of the kiln. If you
use underglaze colours for majolica it shouldn't be a problem.
There is a small glazing studion near Kew Gardens in London that wiil glaze
biscuit ware. So far we have no news of any of the millions of tourists that
visit Kew ever keeling over in the street as they pass the studio.
If anybody can get hold of some old Agfa stripping film they could try
coating irregularly shaped pots.
I think the false alarms on this subject are similar to those concerning the
effects of global warming and I'm sure that the late and great George W.
Bush Jnr. would agree on that one.
Randall Webb
>