U of S | Mailing List Archive | alt-photo-process-l | Re: My own PVA glue sizing experience (attn: marek + the gum woesagain

Re: My own PVA glue sizing experience (attn: marek + the gum woesagain)


I agree with Loris...

I've found that black and blues in general can stain more easily, and especially when they are too concentrated. For example, when printing with Ivory Black, I got staining at 1 gram pigment / 2 ml gum, but it worked perfectly when increasing the gum to 4 ml.

All pigment brands are different, I am told, so you'll have to find the sweet spot for you.

----- Original Message ----- From: "Loris Medici" <mail@loris.medici.name>
To: <alt-photo-process-l@usask.ca>
Sent: Friday, October 23, 2009 11:39 AM
Subject: Re: My own PVA glue sizing experience (attn: marek + the gum woesagain)

Hi Phritz,

I checked again with a wet hard bristle brush and no gum was lifted
until I finally physically damaged the surface. (I brushed very long
time and very hard.) Conclusion, my version of PVAc glue size is
perfectly fine in that sense. Very tough, very durable and keeps the
exposed/developed layer onto itself.

BTW, it's not a good idea to keep the coating solution (gum/pigment +
dichromate) for a day. You'll get "dark effect". Just mix enough for
immediate use.

I'll repeat that your coating solutions seems to be very high in
pigment load; that's definitely not a coating solution to
expose/develop in the normal way, to my eyes. I'd use that much
pigment only if I plan bleach development...


2009/10/23 phritz phantom <phritz-phantom@web.de>:
hi loris,
maybe it's a different recipe after all. i don't have any coating problems
at all, not even at a 1+1 dilution. at 1+1 there is a little beading action
when the emulsion is first applied, but it smoothes out fine, even before i
start with the second brush.

i can't get around the problem with the bad adherence of the exposed gum
(with my caparol binder size)
it took me while to notice (at first i thought it's the strength of the red
layer that overpowers the yellow one), but brushing on another layer on top
of an image, brushes off parts of the layer beneath.
it's a dilemma, single layers print absolutely beautiful, but if i can't
print multi-layer, it's unusable. i've now checked with different dilutions


the bottom strip is the "cold gum" mix. the middle one (not beautiful, but
stain free) is coated the next day with exactly the same emulsion- i kept it
in the closed mixing vessel overnight (also notice the reduced sensitivity).
the top strip is a mix applied freshly, the same proportions/ pigment as
i'm definitely buying a hygrometer now.