U of S | Mailing List Archive | alt-photo-process-l | Re: Another PVA question

Re: Another PVA question



hi keith!
i have exactly the same problem! i wrote a few mails about that earlier (header was somthing like: "caparol size gum woes". search for caparol and you should find them.
you are using the gamblin size. that's a huge disappointment for me. i was using a pva-based product from a different company, called "caparol" and i hoped that switching from caparol to gamblin, this would eliminate the problem. marek said that he doesn't have this kind of adhesion problems with gamblin. and neither did loris btw. with a product similar to caparol.

in my case the exposed and dried emulsion adheres well to the size when still DRY. as soon as it gets wet, it's very vulnerable. a few strokes with a wet bristle brush will brush it off. i've used dilutions from 1+1 (pva + water) to 1+20 and tried brush coating the size as well as immersion sizing with the higher dilutions. adhesion improves with the higher dilutions, but it never gets good enough.

so, maybe this is more a problem of sizing technique than the kind of pva. i remember the video from one list member applying the pva size onto a platinum print. he brushed it in (with a foam roller) very vigorously and while drying it with a fan (iirc).
maybe vigorously brushing the pvs into the paper fibers is the key?

i hope to hear more about the problem, maybe we can solve it
phritz


Keith Gerling schrieb:
OK, this is more troubling. It seems that when I try to hasten the development of a stubborn third layer using a brush, it also brushes off the underlying two layers. That's bad. I'm using Gamblin PVA size, undiluted. Never saw THAT happen with gelatin. Hardened layers were always impervious to anything. Am I doing something wrong here?. Arghh. My preliminary tests were very good and I went and bought 4 big bottles!
On Fri, Nov 13, 2009 at 12:24 PM, Rajul <eyeear@shaw.ca <mailto:eyeear@shaw.ca>> wrote:

I too noticed that PVA incorporated in the ground mix for printing
on Al seemed to leave a rough surface after 3-4 gum passes. The
PVA containing ground was much sturdier than the one without it
but was gelatin-sized.

I have re-coated the prints with PVA and am doing another pass to
see how it behaves. Will let you know what happens.



On 13-Nov-09, at 10:16 AM, Keith Gerling wrote:

I've started experimenting with PVA size for gumprinting and
it seems to be acting a little strange. With gelatin size,
the first layer of gum usually takes longer to clear. With
PVA the first layer clears quickly. sometimes VERY quickly.
As I add layers, I notice that not only does it take longer
to clear, but slight staining seems to be happening. Is the
PVA being washed away? Do others resize with PVA mid-print?

Sorry to change the subject, but I better ask my question
before the meter starts running!