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Re: bubbles in gelatin



On Tue, 10 Oct 2000, Sandy King wrote:

> I size paper for carbon by brushing on a 2-3% gelatin solution (with 
> glyoxal added) with a foam rubber brush about 3 inches in width. 
> First I soak the paper, then place it on a flat surface and squeegee 
> it out. Then, I blot the face with a clean towel to get off all of 
> the excess water. To coat I use about 100ml of the gelatin solution 
> per sheet of watercolor paper, 22x30" size. When the gelatin sets you 
> can dry it on a rack or hang to dry, as you prefer. I often use 
> alcohol to get rid of the bubbles, but more than you, as much as 8 
> ounces per liter of solution.
> 
> This method is much less messy than either of the methods you 
> describe. In fact, there is virtually no mess at all.

What do you "squeegee out" with?  On what paper?  It doesn't rough up the
surface? My squeegeeing has not (yet) been satisfactory.
  
Meanwhile, I haven't tested it as well as I meant to -- tests left
midstream last May need to be started again -- but my experience so far is
that gelatin brushed onto the top doesn't give as good a size for
multiple-coat gum as when paper is immersed in the gelatin, which
permeates it more throroughly. For carbon, I gather you only do one
transfer, but a gum print can have 5 or 6 or more coats -- sometimes with
long soak times. After a couple it usually needs resizing, but gelatin put
ON TOP OF existing color is usually (IME) yucky, makes it look hazy and/or
greasy. I also suspect that another gelatining & hardening will shrink the
paper more if anything can & give more register problems.

Also, I find, not all, but many papers will curl if coated only on one
side.

I'm curious about the glyoxal in the gelatin, however -- that was also in
the unfinished test series -- glyoxal *in* the gelatin vs.separate coat. I
got down to those unfinished tests in the alleuvial layer in studio a few
days ago & found, to my *astonishment,* that the test labelled "glyoxal in
gelatin" was discolored, the edges where there was a build-up of gelatin
somewhat carelessly applied apparently, not visible at the time, but now
VERY discolored.  The "glyoxal separate coat" sheet showed no discoloring.

I soaked the discolored piece in water 24 hours... some lightening in
part of it but most stayed the same. That was Photographer's Formularly
gelatin (basic subject of the tests) -- would all have same reaction?  On
every paper? Who can say?

As Mae West explained, so many tests, so little time... All things
considered, I see no way to avoid the gelatin soak (& the 3 litres of
gelatin I mixed last night were NOT enough) but would sure like better
anti-bubble aid than alcohol.  I think there's one out there...

Judy