On Thu, 2 Dec 1999, Darlington Media Group wrote:
> Keith,
>
> The reason your cyanotype image is fading when the gelatin is applied is
> due to the nature of 'prussian blue'. This compound will fade irreversably
> in any alkaline solution, and I suspect the gelatin or glyoxal/formaldehyde
> solutions have a pH greater than 7. You could check this out with some pH
> paper and adjust the pH of the solution to neutral. The border, being
> denser, will be the last part to fade.
This isn't so -- that is, cyanotype as undercoat for gum is a time honored
practice and many do seem to gelatin size over it, tho I personally have
not. Among celebrity artists who do gum over cyano, those who spring to
mind are Sam Wang, Teresa Van Hatten and Sarah Van Keuren who do or don't
size after the cyano, Sarah does, I do not. In fact a certain famed
publication had an article by sarah, just this past issue, in which she
describes gelatining over cyano.
My suggestion at this point would be that Keith add to the sum total of
human knowledge by doing this with same old, boring, ordinary (that is,
regular) cyanotype. There are definitely some advantages to the "new"
cyanotype, but they are essentially frills.
And PS: the "old" cyanotype is what cited celebrities use. The "new"
operates quite differently and may simply faint (in all senses of the
word) at the sight of gelatin.
Judy
.................................................................
| Judy Seigel, Editor >
| World Journal of Post-Factory Photography > "HOW-TO and WHY"
| info@post-factory.org >
| <http://rmp.opusis.com/postfactory/postfactory.html>
.................................................................
>
> What effect this will have on the 'setting' properties of the gelatin is
> anybodies guess. Or, you could stick with a Pthalo blue gum as an
> underlayer and play safe. <g>
>
> Tony McLean.
>
>
>
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