Re: gelatin and cyanotype

From: Judy Seigel ^lt;[email protected]>
Date: 09/20/04-10:56:49 PM Z
Message-id: <Pine.NEB.4.61.0409202353570.19643@panix2.panix.com>

On Mon, 20 Sep 2004, Christina Z. Anderson wrote:

> Question: I can't remember where I read this, but a book said somewhere
> that cyanotype doesn't "like" gelatin. Does anyone know why this is the
> case, or feel this is the case? Is it just the absorbency issue, that the
> cyano wouldn't get deep enough on sized paper? Or is it another myth?

That was probably me (grammatical correctitude would make that "probably
I," but I agree with Fowler who says that's icky ).

When I first fell in love with cyanotype (circa 1978) we didn't have, or I
didn't know about, all the modern manuals which followed, so I worked from
the old encyclopedias and almanacs. Anyone who has done that knows that
few of the originals agree (tho later books cut and pasted whatever they
landed upon without testing, again not this article). They also didn't
have a really precise 21-step, using folded translucent paper, which
tended to leave a lot to *interpretation*, so even if they had tested,
results could have been compromised.

There was a lot of stuff about things like "preservative" for cyano
emulsion, usually (as I recall) a potassium bichromate, or maybe it was
potassium bromide (I'd have to look it up), which I found usually made
matters MUCH worse. I wrote about and showed many of these tests in the
Post-Factory cyanotype issue (#5).

One of the other variables I tested, or rather two, were the sizes, both
gelatin size (hardened, unhardened) and starch size. I found that
cyanotype *with a continuous tone negative* was ALWAYS, on any paper (of
the several I tested), inferior to the plain virgin paper. (And the starch
size usually useless or degrading. Of course papers were different when
the early books were written, maybe they reacted differently.)

BUT, that was for a finished print in cyanotype, made with a continuous
tone negative. The highlights were washed out, and shadow separation
weakened. BUT, digital negatives don't work the same way -- you don't
have to hold delicate highlights, because each dot is either off or on, no
fragile halftones to wash away, or much less so. My own experience with
tricolor gum is that no single color wants the d-max wanted for a one-coat
print, which would totally block up shadows in the final (tricolor) print.

So it's quite possible (if not probable) that an underlayer of cyano would
be as good or even *better* if somewhat under d-max -- though for a
straight cyanotype, you generally want the longest scale and deepest D-max
possible, no?

Incidentally, Sarah Van Keuren, Mistress Maven Marvel of gum over
cyanotype, wrote in her article in Post-Factory #3 ("Not by Gum Alone")
that she had picked up the trick from a student of preshrinking the paper,
then doing the cyano coat, then adding a gelatin size, then doing a gum
layer or two. But that wasn't with digital negatives, and not color
separations which usually perform differently... IMO the only way to
declare that definitively would be to test with your own materials &
procedure...and not take anybody's word for anything.

chherio,

Judy

> I have been exposing my cyano layer for my tricolor gums on top of
> gelatin/glut sized paper and have not seen a problem, and am wondering if I
> am just lucky this batch. I mean, it wouldn't be hard to do the cyano
> first, then brush coat size on top, but if not necessary...
>
> I also have abandoned using Ware's cyanotype on Fabriano Artistico Extra
> White, an incredibly alkaline paper. It is so alkaline that when it hits
> the vinegar bath it fizzes. . It is downright ugly unless vinegar
> developed, and that is a mess because the vinegar mordants my bathtub blue,
> and since the traditional doesn't require that fuss and produces the most
> beautiful cyan for a tricolor gum, I'm happy. No more lavender dull drab
> highlights.
>
> End of story.
> Chris
>
>
Received on Mon Sep 20 22:57:06 2004

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