From: Judy Seigel (jseigel@panix.com)
Date: 09/05/03-02:14:02 PM Z
On Mon, 1 Sep 2003, Gary Nored wrote:
> I coated several sheets of paper with gum/dichromate
> solution, omitting the ink. To my surprise, this paper
> didn't come out white after exposing to sun and washing --
> it comes out a nice caramel-brown color. Further
> experiments yielded nice photograms of white and brown
> (better than the prints with pigment in them).
This point has been addressed, but here's a generalisation (or
generalization if you have American spellcheck): With my materials and my
working protocol there was NEVER EVER any advantage to "sizing" the paper
with gum. I think some folks think it's easier than gelatin size because
you don't have to watch temp., & harden, and of course there are fewer
variables... But in the words of the prophet, in this case at least, the
lazy person's way is the hard way....
If you set up to do a whole bunch of paper (having done a test run of the
materials first to be certain), and ADD A DROP of KREMER ANTI-FOAM to the
liter of 3% gelatin, then squeegee with a rod against a glass sheet (from
the back) the sizing goes very quickly & the coat will be perfect. (I'm
going to do an exact description with diagrams for the forthcoming #9, but
will answer any particulars asked in advance.) For "rod" incidentally I
use an acrylic towel bar about 1 inch in diamter. Works splendidly.
Of course gelatin sizing by brush or foam on one side only is easier, but
the paper tends to curl & (I find) the size not so even & doesn't hold up
as well...
In sum: Gum as size had its own character and made a few dandy prints, but
I found the yield much lower & with an infinite variety of staining
possibilities, the stain was more trouble to remove (with sulfuric acid,
btw) than the drill with gelatin -- ie., in the long run a much bigger
pain.
One other point: it seemed like someone thought "commercial" or
printer's gums darker than other gums. This is not the case. I found for
instance Varn gum lighter than most... RBG or Philben house gum is also
quite light, as are many others... That is, I find "commercial" or
printer's gums superior to home made, except for an etcher's gum (as from
Graphic Chemical) -- it has an ingredient that's bad for gum printing.
If you start with a gum arabic powder, of course it will be very light,
but besides the nuisance of mixing, there's the problem of preservative.
The lithographers gum we buy by the gallon already has preservative (we
may not want to know what that is, though I suspect it accounts for much
of the difference between commercial gums).... and no matter what the
label says, I've found it keeps well, for my purposes remaining more or
less the same for years.
Judy
This archive was generated by hypermail 2.1.5 : 10/01/03-03:08:59 PM Z CST