From: Richard Knoppow (dickburk@ix.netcom.com)
Date: 05/16/00-09:40:24 PM Z
At 10:15 PM 05/16/2000 -0500, you wrote:
>I'm just wondering, is he soaking in Pakosol or the like before squeeging it
>to the glass? I thought that prints first soaked in that
>solution aren't supposed to stick? Maybe hardening the first few layers of
>gelatin to create a base for the other layers to sit on and then after
>applying subsequent layers of gelatin, soaking the print in Pakosol and
>squeeging it to the glass might prevent it from sticking and give it a
>glossier finish. I realize that's quite a bit of work. I'll see if I can try
>it out tomorrow as I've got all the supplies, just not much time as it's
>summer cleaning time in the lab, ouch. Amy Cutting
>
Earlier thread snipped...
Perhaps it would be helpful to understand the structure of conventonal
printing paper. The paper is first coated with at least one coating of
rather hard gelatin containing a dispersion of Barium sulfate. Sometimes
several coatings are used. The emulsion is coated over this. Usually a
layer of gelatin is coated over the emulsion to protect it from abrasion
and as a carrier for anything used to make a matt surface, often starch.
Papers meant for ferrotyping do not have any matting agents in the
overcoating. (Paper for Carbro bromides has no overcoating).
The gelatin substrate with the barium reflecting surface is made very
smooth for glossy papers. The Baryta layer, as it is called, can be
callendered. I know it is for textured paper but am not sure if it needs to
be for glossy. The absence of this substrate may be why getting a
satisfactory gloss is difficult with an alt print. It may be necessary to
use a couple of layers of gelatin, one quite hard one and another softer
one coated over it. I am guessing at this.
Pakosol and similar glazing solutions are probably only mixtures of
wetting agents with perhaps the addition of some Glycerin. I can't find an
MSDS for Pakosol, it would be interesting to know just what is in it.
As Rod points out surfaces other than bright chrome need some
preparation beyond cleaning. Glass requires polishing with talc and waxing,
I've never had much luck with it. Enamel requires waxing with an
appropriate wax. There are several formulas in the older books. Since Rod
has had good results with this type of plate he can probably suggest a
satisfactory wax formula and procedure.
While it is sometimes suggested that the emulsions of conventional paper
shold not be hardened every one of the older books, written when
ferrotyping was common, suggest hardening and give lack of hardening as a
common cause of failure. Someone trying this on an alt processes print
needs to experiment with just how hard to make the overcoating.
---- Richard Knoppow Los Angeles,Ca. dickburk@ix.netcom.com
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