> Judy
> At times I've used a microwave
> oven to speed up drying without apparent ill effects . Have you every heard
> of ill effect from such a quick drying technique.
Well I've set the paper on fire in the microwave, & that was an ill
effect. I suppose one should wait til it regains ambient moisture before
making first coat of a planned multi-coat gum, because it will probably
expand somewhat. If the quick-drying per se has an ill effect, who knows?
Only a chemist & they don't REALLY know what happens, they only know theory!
(:-)))
> With all this talk about substitutes for gelatin sizing, I have begun to
> worry that my use of Knox's gelatin (used in food preparation) may be causing
> some of the inconsistancy. I found in a chemical catalog two versions of
> gelatin hard and soft 250 and 50 "Bloom". From a posting by Terry I see that
> his deionised ossein is 260 Bloom, is 250 close enough and beside which
> what's a Bloom.
My tests comparing Knox's gelatin with "photo gelatin" showed the Knox's
cleared better in all variations (or showed no difference). However, one
batch of Knox's could differ from the next. My hunch is that other
variables are more significant, however, such as temperature and
humidity and what the guys at the waterworks took it into their heads to
put in the water that day. Also, when you say "inconsistency" do you mean
with the same color? Because each pigment has a different chemistry, and
the effects aren't inconsistency, they're reality.
However, speaking of water, I ask you deionised ossein mavens: What is
to be gained from deionizing the osseins and then mixing the stuff with
tap water, which is chockablock with communities of all kinds, the living
and the dead -- or do you use distilled? And if so, at what point do you
revert to tap water? If you don't develop in distilled you're
contaminating your ossein at that point, no? And if you do, how much can
you lug home from the supermarket?
And let me add that although I have not tried distilled in developing
gum, I did try it when in extremis on VDB. Lifeless prints. Process needs
those salts, apparently.
Judy