Re: Modified Zia Formula


Jeffrey D. Mathias (jeffrey.d.mathias@worldnet.att.net)
Wed, 12 May 1999 00:31:42 -0400


Carl Weese wrote:
> ...
> Humidity not only plays a big role, but the role it plays changes
> dramatically with the paper choice. I suspect that careful control of
> procedural matters like matching the humidity to the paper may be
> significantly more important to overall quality and control than
> chemical tweaking,

I suspect that if the chemistry is "right" a paper will work at most
humidities. I have already found that while the Crain's "platinotype"
had problems at 70 % RH with the published formula it printed fine with
the proper proportions of salt and metal and more of it. It seems worth
while to try tweaking the chem before giving up on a good paper.

Eric Neilsen wrote:
> ...I think that the water is doing something during the process that is causing
> the foggy milky look....

That foggy, milky appearance I had refered to IS due to lack of enough
chem, not water related. I have reproduced the results, and what I have
called milky only occures when the chem is short. I use distilled water
for the coating chemicals and 0.5 micron filtered tap water for the
clearing and washing.

I hope to be able to write up some results of chem tweaking tomorrow.
Although I will address one issue now. Eric had mentioned that Mike
Ware had suggested the concentration of the Ammonium Ferric Oxalate to
be 60% rather than 40%. I have tried this along with various metal salt
strengths. At first look, I have not noticed difference in the print
quality or characteristics. However, the 60% solution does seem to coat
rather "thick" and it may tend to sit on the surface of the paper
causing some blotching problems. The blotching may be avoided by
pre-humidification, spreading the coating completely, and careful drying
of the coating. This does take some extra effort, and with no
difference in printing, and with the use of more material: My
recommendation is to use the 40% solution.

-- 
Jeffrey D. Mathias
http://home.att.net/~jeffrey.d.mathias/



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