Re: Another PVA question

[Keith Gerling <keith.gerling@gmail.com>]

phritz,

In my case the dried layers are very sturdy while applying more gum,  even with vigorous application.  It is after the print has soaked that the gum gets soft.  This goes against everything I have seen with gum.  Usually, if you get a good hard layer of gum, nothing short of bleach will soften it.  The strange thing is that the gum seems to be affected but not the PVA.  Case in point:  Over a layer of yellow I coat red.  Not used to PVA, I get sloppy and let an air bubble leave a red mark undeveloped.  Put the print back in the water, but when I take it out there is red pigment where the bubble was.  I brush away the red (didn't need it there anyway) and the yellow comes with it.  Later, I apply blue and it develops fine.  No staining where the blemish is.  As if the PVA was still there.  So why did the yellow get soft? 

keith

On Fri, Nov 13, 2009 at 1:16 PM, phritz phantom <phritz-phantom@web.de> wrote:

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!