[alt-photo] More on gum print

[Donald Walker]

I size with Knox unflavored gelatin and chrome alum.  3 packets of gelatin
(~21 gms)  in 750 ml distilled water.  The remaining 250 ml of water I heat
in a microwave for about 30 seconds -- hot, not boiling.  Into this I
dissolve 2 gm of chrome alum.

I let the gelatin soak in the cold water for about 2 hours, 3 if its cooler.

I use a 1.5 ltr Crock Pot to keep my sizing hot (it has other uses in the
studio as well, just don't use it for cooking!)  Once the gelatin has
completely swelled and I'm sure I won't have any granules left over, I turn
the crockpot on high and let it do its thing.  When the gelatin is ready, I
still in the chrome alum solution.  Some sources suggest you should let the
gelatin/alum solution stand for a couple a few days afterwards but to be
honest, i haven't notice a difference one way or another.

I use Fabriano Artistico paper, which I pre-shrink by soaking in hot water
for 30 minutes).

I give each sheet one coating of gelatin, let it dry completely, then a
second coat.  When dry the second time I rinse in cold running water for
5-7 minutes to wash out any chrome alum.

Of all the sizing methods I've tried, including variations on acrylic
medium, etc. this seems to work the best for me.  Plus with reasonable
caution, until glyoxal or formalin, you don't need industrial ventilation..