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

[Trevor Cunningham]

  I just coated some paper with the rabbit skin glue and it it produces 
a nice silky smooth surface...hopefully the gum doesn't slide off. I 
know someone said it's brittle, but it soaked right into the paper. If 
it's not consistent this time, I might try diluting the solution a 
little and go from there.

Thanks for all the input gang. I'm just happy to have chemicals, but 
it's the other little things and living in strange places that make me 
wish I was more of a MacGuyver...thought I feel more like a MacGruber 
(if anyone follows SNL anymore)

On 9/10/10 5:50 PM, Peter Friedrichsen wrote:
> 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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