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

[zphoto at montana.net]

Thanks so much for this info, Henry! And you even measured..

My prints are too big to get away without preshrinking, plus I do not 
find that step horrible.

I, too, found that the paper laid flatter with PVA vs. gelatin for 
some reason.

Interesting the difference in shrinkage between the papers....
Chris



On Monday 03/22/2010 at 9:23 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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