Tom, look at it as an opportunity to do a controlled variables test! I
can't wait to hear...
> I had good luck with the Photographers Formulary gum, but eventually
> changed to the Daniel Smith. I use the cheaper of the two gums available
> under that brand name, it looks like used motor oil, but works great???
I found that their Premium gum arabic, which sells for almost 3 times the
price, builds up an unattractive gloss by the second or third coat. I
destroyed a print trying to rub it off. Didn't use it after that.
The "used-crank-case-oil" look of the cheaper Daniel Smith gum, just
called "Lithographers gum arabic" look is a jolt when you first see it
My theory is that the impurities *burn off* in the exposure... (well, it's
a theory). One friend said he tested it with yellow & it didn't degrade
the color, but another expert printer (also on this list -- hello ??!!)
said he found dark gum did affect the pale colors. I haven't noticed
that, but haven't made a test, such a slight degradation not being an
issue in my own work... but it would be interesting to know, just for the
record, so maybe ....
Incidentally, there's a batch number on the gallon container, so when I
found I liked the first gallon I was able to request 2 more from the same
batch. If I change plans before it's used up, I figure I can sell it as
crank case oil.
> I also had good luck with BFK (and Tri-Ess "hard" gelatin and glyoxal), but
> eventually settled on Lana paper (clear a little bit more and I liked the
> surface texture).
Tom, tell me again which "Lana" paper you're using. I know we had this
discussion, but the fact that I used a paper called "Lana" that had no wet
strength at all and was quite thin, has confused the issue in my mind. Who
makes it? What is the weight like? You say you liked the surface
texture... such as?
[Tom's gum printing axioms]:
> 1) Coating technique, learn that less is better. Use as little solution as
> possible.
>
> 2) Paper, settle on one or two papers and learn them. Changing paper will
> change everything else.
>
> 3) Sizing and hardening. I can only assume that this is another water
> issue. Judy and I got entirely different results. She got good results
> with Knox food gelatin and poor results with hard gelatins, I got exactly
> the opposite??? And yes, I did repeat that test??? But I think everyone
> who uses gum and gelatin has gotten better results hardening with glyoxal
> than with the old standard formalin.
>
> 4) Paint, not just a brand, but individual colors vary greatly in usability.
>
I pretty much endorse Tom's four axioms of gum printing as above, tho
on #2 I'd have to say do as I say, not as I do... I'm always flitting
from paper to paper, very inconstant I know, but .....
As for the hard gelatin vs. Knox... the hard gelatins I tested did work on
one or two papers, just not the ones I was interested in. But what occurs
to me now -- surely each gelatin is different, I mean beyond just hard and
soft. Where did you get your hard gelatin? The ones I tried were the
deionized ossein and some ("porcine product") from a source I forget now
referred by a carbon printer.
cheers,
Judy