Re: old cyanotype formulae

[CCBaggett@aol.com]

Judy,
       I agree with you. Alberto asked for the old formulas and I gave him what I had. I can't find my copy of Mike Ware's book which I think is the best current reference on cyanotype. Thanks for ponting out the risks associated with these old formaulas.
Cheers,
Charlie

In a message dated 5/21/02 2:44:35 AM Eastern Daylight Time, jseigel@panix.com writes:


> On Mon, 20 May 2002 CCBaggett@aol.com wrote:
>
> > Photographic Facts and Formulas  E.J. Wall dated 1924
>
> CUT
>
> "Brighter prints are obtained by the addition of 0.5% of
> > Oxalic Acid to the above; the paper keeps better if 0.05%  of Potassium
> > Bichromate is added."
>
> Potassium bichromate as preservative for cyanotype emulsion may be true on
> the planet Mars... but my finding was that it actually made a terrible
> print under most circumstances... The variables included size added to the
> paper, and which size (gelatin or starch), also how long the emulsion was
> on the paper, and how long the size had been on the paper, among others..
> (I showed some of them in the "cyanotype issue" of P-F, #5, page
> 31).
>
> In fact I found cyanotype poster child for old formulas not printing as
> stated.... My guess is that none of the workers then had the Internet and
> didn't realize how many variables there really were. If something "came
> out" for them in one set of conditions, they assumed it was a universal.
>
> The old books are riddled with stuff like that.
>
> Judy