Re: Gum questions

Judy Seigel (jseigel@panix.com)
Tue, 2 Jul 1996 21:04:44 -0400 (EDT)

Herewith comments on several gum questions:

On Wed, 3 Jul 1996, Albert Strauss wrote:

> 1. Can anyone recommend a decent brown pigment(including brand).
> I have had very poor luck with burnt sienna, and van Dyke in Rowney
> and Grumbacher.

Al, what's "poor luck"? A few years ago I tested all the watercolor burnt
sienna's I could find on the market -- Winsor Newton, Rowney, Schmincke,
Holbein, Liquitex (which had a watercolor at the time) & some others I
probably forgot. Of these, for density of color & good clearing the Rowney
was best. Maybe they're changed it, maybe it's incompatible with
something else you're using, or maybe it doesn't do what you want....

> 2. Can anyone comment on the effectiveness of gelatin sizing by sponging
> one side as opposed to dunking, and the effectiveness of hardning by
> including the formalin in the gelatin instead of a separate bath.

If I want to size just a few sheets, it's lots easier to apply with soft
hake brush than to deal with the tray and the drips, especially as a big
sheet of paper needs an enormous tray-full. However, especially with a
thinnish paper, with gelatine on one side only, the paper is likely to
curl up in a very annoying way. This can be controlled by applying another
layer of gelatine on the back of the sheet after the first coat has dried.
Ultimately you could say that's as much trouble as dunking in the first
place, but at least you don't need a trayful.

However -- and this is in the archive! -- don't use formalin, use glyoxal,
for reasons of ear, eyes, nose & throat.

> PS: I certify that I have been to the archives and FAQ and have not found
> answers to the above.

As for use of glyoxal, which I'm also asked about, here's how I've
been using it: Add 25 cc of the 40% solution as it comes from the
supplier to a litre of water. Soak gelatined (& dried) paper a few
minutes. Hang to dry.

For only a few sheets, I've found it works fine to mix up 50 or 100 cc or
so (2 1/2 cc to 100 cc water) and brush onto the dried gelatined paper.

As for adding the glyoxal (or formalin) to the gelatine, I'm
curious about that, too, have never done it.

A small problem with the glyoxal, BTW, is that the working solution only
keeps for a matter of days. After that it gets globs in it -- even unused
solution mixed in distilled water (as I mentioned a while back & if that
isn't in archive, it's sabotage!) So plan your hardening in a bunch.

Cheers,

Judy