[alt-photo] Re: I know, another sizing question

[Peter Blackburn]

A casein "emulsion" can be made directly from fat-free cottage cheese. Rinse away the whey and use ammonia
to break down the remaining curd until reduced to a luscious creamy white goop.
 
I've never used it as a size, but it is a wonderful alternative to gum arabic for printing.  

Cheers!

Peter J. Blackburn

 
> Date: Fri, 10 Sep 2010 10:50:54 -0400
> To: alt-photo-process-list at lists.altphotolist.org
> From: pfriedrichsen at sympatico.ca
> Subject: [alt-photo] Re: I know, another sizing question
> 
> My results with Elmers PVAc have been 
> unsuccessful since,as Loris points out, it will 
> not resist water and will fail as a size.
> 
> I did some digging some time ago (an earlier 
> post) and found that the Gamblin PVAc is a 
> chemically modified beast that greatly improves 
> water resistance of standard PVAc, so it works. 
> Trial and error runs from paint/hardware store 
> products may eventually yield success as Loris 
> has found, but even if you luck upon the right 
> PVAc type, you still have to deal with the 
> unknowns of the ageing of a sizing from a product 
> with unknown composition and pH.
> 
> Re Casein as size
> 
> I haven't used it as a size but I do know it will 
> form a very water resistant coating once 
> hardened with Glyoxal or Formaldehyde. These 
> hardened films are a little more brittle than 
> gelatin films, and the films forma mat finish 
> with may provide more tooth good or bad.
> 
> I think if you had a source of sodium caseinate 
> powder, then it may be worth experimenting, but 
> to precipitate the casein from skim milk every 
> time you need to size would be more effort than 
> it is worth unless there were some clear 
> advantages in terms of performance or 
> convenience. The only clear advantage I can see 
> off the top is that the caseinate solution is 
> liquid at room temperature and avoids the warming step of gelatin sizing.
> 
> Re whey
> 
> As was mentioned, the whey (clear solution) that 
> is left over after the casein is filtered out 
> also contains hardenable protein but it is mixed 
> with lots of lactose and other impurities. I know 
> you can purchase purified whey protein isolate 
> which is used in foodstuffs and as a body 
> building powder. From what I understand it 
> suffers from poor adhesion and forms a film that 
> is brittle and flaky but I have never tried this 
> as a sizing. It does have the advantage that it 
> is very soluble in water and you can make 50% 
> solutions without too much viscosity.-kind of like gum arabic in this regard.
> 
> Peter Friedrichsen
> 
> At 06:14 AM 09/10/2010, you wrote:
> >If I'm not mistaking, Elmer's glue was used in 
> >place of gum or something - that means it isn't 
> >waterproof; something good for a gum 
> >replacement, but not good for being able to used 
> >as a sizing... As I said before, you should look 
> >for something that is PVAc based, clear (when 
> >dried as a film) and waterproof. See hardware / 
> >paint stores, I buy mine from a paint store, 
> >dilute it 1+4 and use - paper's ready when dry, 
> >and the sizing is very robust; I had a student 
> >put 9 layers w/o any staining... Regards, Loris. 
> >2010/9/10 Trevor Cunningham 
> ><trevor at chalkjockeys.com>: > Â Maybe not? I read 
> >in the manufacturer's details that it has a pH 
> >of 4.7...I > know the Gamblin product (which I 
> >can't get) is pH neutral. Would diluting > the 
> >glue with distilled water help to raise this 
> >number a little? Mix a > little baking soda into 
> >the solution? > > On 9/10/10 9:25 AM, Trevor 
> >Cunningham wrote: >> >> Â Is good old fashioned 
> >Elmer's school glue a suitable PVA glue? That I 
> >can >> find. 
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