Re: air bubbles in gelatin

Pollmeier Klaus (100561.2417@CompuServe.COM)
09 May 96 17:51:36 EDT

Luis Nadeau describes several methods how to coat gelatin on paper in his book
'Modern Carbon Printing'.

If you allow the warm gelatin to stand for half an hour or so at 50-60C, the air
bells in the beaker almost should have disappeared. Soak a thick (1 cm) glass
plate in hot water, take it out and quickly squeegee the (presoaked) wet paper
onto it. Then fill the amount to coat one sheet into a smaller glas beaker which
is stored in hot water if not in use. Take care to poor the gelatin on the paper
from very short distance. Take a fine tooth comb with a perfect straight edge to
spread the gelatin instead of a brush or a glas rod. This creates no bubbles if
done properly. But even with a 1 cm glas, the gelatin may gel too quickly, so if
available, use a plate or tray warmer under it.

You could also poor the hot gelatin onto plexi, spread, let gel, put the plexi
in cold water in which the paper is allready for a while, pull both out together
and let the paper dry on the plexi over night. The next day you can peel off the
paper with a perfect smooth gelatin coating. Any bubbles that first were on the
gelatin surface now are between the paper and the gelatin and will not (or much
less) show up in the print (as long as the gelatin coating is thick enough).

Of course, all supports have to be levelled perfectly and you will have to work
concentrated and rather fast...

Think of giving some dichromate into the gelatin, so you don't have to sensitize
and wait again for hours... But the sensitized paper cannot be stored except in
a deep freezer.

Klaus Pollmeier