Re: Gum : dichromate concentration

On Mon, 1 Dec 2003, Christina Z. Anderson wrote:

> However, I, too, as Sandy is, am puzzled by the incredible variations we are
> reporting, which is probably exactly why every time the subject of gum comes
> up on this list we all get tizzied up. Maybe it leads back to the
> acidity/alkalinity thing that we talked about a while back...and, as Judy
> was reporting a 3-6 stop variation of exposure in different gums, that might
> account for some of it. Who knows.

OK, be glad for the tizzies, they actually add info, not to mention spice
of life... beyond simple Q & A. And, as I find with editing, they will, if
we persist, often bring out crucial info -- as the business about
different kinds of digital negatives printing differently may be. Would
we have thought of it if not for tizzy?

Meanwhile, however -- Sandy -- do not not not look to baume for answers.
Sorry. For several reasons -- for one thing, if we all use different
ratios of dichromate solution, at different strengths, and with different
amounts of water added (as I and it seems others do)... there goes your
"baume" in a cocked hat -- even IF that were the answer, which as far as I
can tell it's not.

In fact I reported this on the list a couple of years ago. Finding I had
3 gums supposedly with the same baume but with distinctly different
speeds, and wondering if the label "14" was a lie (the obvious suspicion)
I took samples to the chem lab at school & got the use of a gorgeous
antique glass baume meter -- they all indeed registered 14, even tho they
seemed possibly to pour with a different amount of viscosity.

I tried to check pH as the key, but found no factor I could blame there --
no correlation -- tho my pH meter wasn't state of the art (to put it
mildly) so I can't quantify confidently. At that point I left the question
to mystery of the spheres, at least pro tem -- but warn again that you can
not not not simply "deduce" any of it, because it's probably not yet in
our knowledge. In fact that could bring one dangerously close to Anderson
(and OTHERS') "seems logical disease"... where a deduction is made by
"logic" that is later found not to apply..... as we can read almost weekly
in the NY Times science section.

PS. Note Jack B's suggestion about the unsized paper just now... the
comment of practice, not theory. In fact he reminds me that when I tested
sized vs. unsized paper years ago, the sized was slower -- because the top
steps slid off.

Judy
Received on Mon Dec 1 16:17:19 2003