[alt-photo] Re: pre-shrinking and PVA size

[Diana Bloomfield]

Hi Henry,

Thanks for the update. That's really helpful.   I do remember first  
attempting the PVA on Fabriano, and it offered up that plastic-like  
coating, which you mention--  and which I just don't seem to get on  
the Rives.  So I'm guessing it sort of sits up more on the surface of  
the Fabriano, and perhaps sinks a little more into the Rives paper(?),  
or is somehow absorbed differently with Rives.

I'm also guessing there's a lot more internal sizing in Fabriano than  
with the Rives paper, so maybe that might make a difference, too (and  
why you'd get patches that were difficult to coat on the Fabriano)--  
especially since you didn't pre-shrink, and so didn't lose any of the  
manufacturer's sizing.

I was really surprised by Paul's post-- which I read only briefly  
yesterday, so maybe I need to go back and re-read that to ensure I got  
it right-- but I was really surprised that he didn't have to size the  
Rives and got no staining.

Anyway, I have some Fabriano here, so maybe I'll try that at your  
dilution.  Thanks.

Diana
On Mar 22, 2010, at 11:22 AM, Henry Rattle wrote:

> Just finished some trials with PVA size on Saunders Waterford (300g
> hot-pressed) and Fabriano Artistico (300g CP, traditional white).  
> Starting
> with virgin (not preshrunk) paper, the sequence was size, then  
> (coat, dry,
> expose, 1 hour in water at about 20C, develop with spray, dry) for  
> each of
> three coats of gum/pigment.
>
> In passing, I measured shrinkage. After the treatment above, the FA  
> shrank
> 0% in one dimension and 1.1% in the other (across the 12x9 sheets I  
> was
> using). The Waterford was 0.4% in one dimension and 1.2% in the other.
>
> My normal print size is about 9x7 inches, so a 1.1% shrinkage on the  
> short
> dimension puts me about 0.8 mm (sorry for mixed units) out of  
> register at
> the top and bottom edges of the print, assuming I register for the  
> centre.
> Whether this matters to you depends on the subject matter, I guess -  
> but I
> think I'll continue to preshrink my paper, though not in hot water.
>
> As to the Gamblin PVA size, I was very pleased. I coated successive  
> 3 inch
> wide strips of each single sheet with full-strength, 1+1 and 1+2 PVA  
> size,
> then coated and developed three-colour gum as above.
>
> The full-strength PVA, though I tried to coat thinly like Diana, had  
> a few
> patches which were hard to coat. It also had the slightly plasticky  
> surface
> that Diana objects to.
>
> At 1+1 both the Saunders and Fabriano coated easily and cleared very  
> well.
>
> At 1+2 the Fabriano cleared well and the Saunders not quite so well.  
> Both
> cleared better than my control sheet, which was Saunders which had  
> been
> brush sized with gelatine/formaldehyde. That was my standard till  
> today, but
> from now on I'll be using FA/PVA.
>
> The other plus for the PVA was that there is far less of a fierce  
> curl on
> the dried paper than you get with gelatine, either brushed or  
> soaked. Much
> easier for the next coat.
>
> With best wishes
>
> Henry
>
>
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