[alt-photo] Re: IDEA? NEW ALT PHOTO BOOK

[Paul Viapiano]

Christina...

These are all very good questions.

Personally, I like to put down at least two layers before PVA sizing. I have 
noticed that the layer after the size has a harder time adhering, hence I 
should probably expose more or develop for less time. But then again, there 
are so many variables going on in any print, that I haven't taken the time 
to try and pin it down.

I think that someone (Keith Gerling) also mentioned a while back, that he 
found layers were less stable when re-wetted. Would things be more stable if 
we exposed the print to UV after drying each layer? Just a thought here...

I don't know if the print really sits on top of the PVA any more than the 
gelatin. I look at it as just helping the already-sized paper along as its 
original size gets diluted with repeated soaking. This is all very 
unscientific of me but is what I'm thinking.

Paul

----- Original Message ----- 
From: "Christina Anderson" <zphoto at montana.net>
To: "The alternative photographic processes mailing list" 
<alt-photo-process-list at lists.altphotolist.org>
Sent: Friday, April 23, 2010 6:31 AM
Subject: [alt-photo] Re: IDEA? NEW ALT PHOTO BOOK


> Bob,
>
> I think it could be a good thick chapter of a book...
>
> I am probably opening up a can of worms here...
>
> I've been using the Gamblin PVA size now and taught it to my class this 
> semester in place of glutaraldehyde hardened 2.8% gelatin (6ml of 2.5% per 
> liter), and it is a great teaching method and really user friendly.  Boy 
> was my life easier--no hot plate, massive sizing day, mess, toxicity.  PVA 
> you can just "size as you go". It is the "magic bullet" of teaching for 
> sure.
>
> I use it 1+2 on Artistico.   I found more issues with staining with PVA 
> than with glut/gelatin but that I think is specifically related to having 
> to determine the dilution of PVA for each specific paper.  I almost think 
> Fabriano might benefit from either a 1 + 1.5 or an intermediate layer of 
> sizing between multiple coats. But at a point, then, PVA becomes too slick 
> and plasticy.
>
> However, after having worked with it all semester I slightly prefer 
> glut/gelatin.  **But** I am not sure I prefer the latter enough to go to 
> all the trouble to do it.  With tray sized sheets gelatin is no big deal, 
> but with 15x22 size sheets it is a pain. PVA wins, hands down, for 
> user-friendliness.
>
> I will be finishing up two large gum projects this summer so we'll see by 
> the end of summer how I feel--if I go back to gelatin in my own work, in 
> other words.  I will continue to teach the non-toxic PVA method, but parts 
> of me think I should still at least show students traditional sizing 
> because of a concern I am feeling.
>
> My concern is this:  when I take a print out of the water to hang to dry, 
> even the border of the print is what I would call "unstable"--meaning a 
> fingerprint on it will mar it quite extensively in a way I have not seen 
> with gelatin sized paper. Anecdotally, a rewetted PVA print SEEMS also 
> less stable--layers still manipulatable.  Is that an issue?  I don't know. 
> My question is does each layer you do of dichromated gum on top of a layer 
> of previously hardened gelatin also affect the gelatin below (another 
> colloid) and does it, in fact, affect a layer of PVA in the same way?  Or 
> can the layer of gelatin even GET rehardened repeatedly with each 
> succeeding layer of dichromated gum or is it hardened once and for all 
> with the glut and that is it--successive layers do nothing?
>
> Or is this just a "hydrophilic" thing, or that gum is (how would you say) 
> "attracted" to PVA in the same way it is to a surface of gelatin?  Are, in 
> effect, PVA and gelatin truly interchangeable in sizing or is it possible 
> that each layer of hardened gum has better adhesion to a layer of gelatin 
> vs. a layer of PVA, probably only visible at the microscopic level?
>
> Maybe the scientists of the list can answer these questions and put my 
> mind to rest, because my lurking fear is that the gum print on top of the 
> PVA may not be as stable in the long run as one on top of gelatin.  A 
> non-scientific test I will do in a couple months is soak a PVA'ed print 
> and a gelatin-sized print, old ones, side by side, and scratch and see the 
> results. But I don't know if that proves anything.
>
> I hope someone will come on list and say this fear is completely 
> unfounded, that both sizings create equally stable final prints. But I am 
> worried the gum print sits on top of the size instead of melds into it.
>
> I have no answers, just asking the hard questions....on this quest for the 
> most perfect, easiest size.
>
> Now, as far as other processes aside from gum....salt...hmmm....
>
> Chris
>
>
> Christina Z. Anderson
> christinaZanderson.com