Judy Seigel (jseigel@panix.com)
Thu, 03 Jun 1999 20:56:40 -0400 (EDT)
On Thu, 3 Jun 1999, Wayde Allen wrote:
> > If the bloom v. dichromate is X factor with use of one gum arabic it
> > might very well be 2x with a different gum arabic.
>
> I have a really stupid question, is there even such a thing as a bloom
> rating for gum arabic? I'll have to go look at my bottle of gum, but I
> thought that gum was rated primarily in degrees Baume'. I can't exactly
> envision a bloom test for gum.
Maybe I was careless terminologically there, but I do know as a FACT, that
two gum arabics which measure 14 degrees baume (and not only on the label,
I measured the baume myself in the lab at school) have VERY different
"speeds," that is with all other variables tightly controlled and the only
difference the gum, one was TWICE as fast as the other.
In fact the 3 main gums I use have each a different "speed," although all
are 14 baume.
My statement about "2x factor" refers to the fact that I'm unable to
consider the hardening in a vacuum, but only with use of particular
materials. I was assuming that the test of the gelatin hardening would be
(in my case) in use with a gum. But you're right, Wayde, for gum printing
the hardening of gelatin may be relatively irrelevant.
> > It seems possible that gelatin plasticized like roll film would not
> > differentially harden and melt in the ready way carbon tissue does.
>
> OK, why not? You could be right, I just don't know ... yet <grin>.
Well, whenever I have (accidentally or on purpose) stripped emulsion off
film, it came off right to be bone in one piece. Maybe, probably that's
simplistic. Good work for you if you show that's wrong.
Judy
This archive was generated by hypermail 2.0b3 on Thu Oct 28 1999 - 21:39:36