Re: PVA vs. PVA

Giovanni Di Mase wrote:
>

>
> 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?

If you're talking about using Elmer's for the colloid in the gum
process? I wouldn't expect that to work, since it's not water soluble
once dry.

>
> 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

Clarification: I didn't mean to say all PVA glues are made of PVAcetate,
just the one I happened to buy. Gloy is water soluble, although
difficult to get in the US I understand. Someone was kind enough to send
me a bit so I could try it; I found it to work almost exactly like gum.
I mixed it just as I would mix gum and it printed nicely just as the gum
would print. So if you had some PVAlcohol glue and wanted to print with
it, I would suggest starting with your gum protocol, and refining from
there.
 
I have had much better results with acrylic as a size than Judy reports,
and I wonder if perhaps when she did her early tests, she used matte
medium, which certainly would have the effect she describes. I can't say
I've used acrylic a LOT, but when I have used it for convenience, I do
get continuous tone in the gum print.
Katharine

 
>
> 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 12:05:25 2005