Re: PVA vs. PVA

Thanks Judy,

Your opinion is very helpful to me.

Any idea what the stock ratio (dilution, pigment and bichromate) and would
be using glue (any Elmers or Gloy) instead as arabic gum to start with?

I am assuming that Gloy is manufactured out of PVA acetate as all other
glues and as I read from Katharine it is not water solubable therefore could
not replace the arabic gum, but I have also read the opposite

I am going to try anyway and compare to the PVA alcohol glue, I just need to
have some clear ideas from where I am going to what I can find.

Giovanni

----- Original Message -----
From: "Judy Seigel" <jseigel@panix.com>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Sunday, July 31, 2005 10:33 PM
Subject: PVA vs. PVA

>
> I've been trying, & failing, to follow the PVA thread(s) because they seem
> to switch between use for sizing paper instead of gelatin and use as
> colloid instead of gum arabic.
>
> When I began testing for gum (more years ago than I have actually been
> alive) it was popular in the (then) new manuals to suggest dilute acrylic
> medium or dilute acrylic gesso (liquitex) as substitute for the gelatin
> size - as being much quicker and easier.
>
> When I tested with a 21-step I found that as size *for gum printing* none
> of them in any dilution worked as well as gelatin for paper size -- for
> continuous tone.
>
> They simply did NOT do smooth highlights AT ALL. The gesso size also
> tended to both flake and turn the color to pastel. (Which figures -- it
> was in a way *mixing* white, which makes a *tint*.) (If memory serves, I
> showed some of those test strips in P-F #1, or maybe it was #2.)
>
> However, stochastic or halftone negatives were a different story... Using
> halftone color separations, I got some fine results with diluted matte
> acrylic (1 to 10) to size the paper... but that was basically because it
> was so much *easier* than gelatin size. Results were no better & maybe
> somewhat less certain than with gelatin.
>
> There are English gum printers who use (or used) Gloy gum (PVA) for gum
> arabic and swear by it (eg Terry King does, or did). I was never able to
> get Gloy to do continuous tone *by still development* but that seems
> to be a variable of personal virtue, humidity, and/or the paper and size
> combo. (A hard, ie, 300 bloom, gelatin size without hardener has very
> different results from the Knox with hardener gelatin size, for example.)
>
> In other words, theorizing is probably futile, if not counterproductive.
> Materials respond so differently in various combinations that generalities
> say nothing -- or only in theory (& we all know that business about the
> bumblebee). Of course it's nice to find a magic ingredient without the
> tedium of actual trials -- but odds are against it.
>
> As for Kevin Sullivan's work with whatever it was as size -- was that for
> gum? IME sizing for gum is a whole other world than sizing for pt/pd, or
> other -- no correlation.
>
> And Henk, tell yr friend that folks use lavender, carbolic acid, glyoxal &
> thymol as well as formaldehyde to preserve gum -- but if you mix it fresh
> & use it in a day or two, no preservative necessary. Also, if you don't
> mind the variables -- some folks (if I recall Demachy (?) among them), may
> prefer acid,that is, "spoiled" gum.
>
> Judy
>
Received on Fri Aug 5 12:02:25 2005