I guess, Glenn, my first question for you is: How exactly are you sizing and
pre-treating your paper?
more:
In my work with gum I have always begun with the lightest color first - it
just seems to work better this way, and by the time you get to your third
color, you won't be having problems exposing for your shadows with the
darker colors last.
I have used lamp black and vowed never to use it again, for exactly the same
reason: It needs too long an exposure!!!! I used an appropriate amount of
powdered pigment (2.5 g for 15cc each of gum arabic and amonium dichromate
mixture), and it all fell off in the developing for me also.
If your coat was so thin, my first guesss is that you weren't using enough
gum, but it sounds more like you were using way too much pigment. As Terry
mentioned, a pea sized amount, and especially of lamp black, would be
sufficient - what is the size of paper you are trying to cover?
What is the mixture for your sensitizer?
The wierd odour you smell is most likely the normal odour of the gum arabic,
but I can't be certain.
An alternative to lamp black is the ivory black, and though it may not yeild
such a rich density, you may find, as I have, that it is a hell of alot
easier to work with! This isn't always the goal, I know, to make it easy,
but I was willing to give it up!
Ok.
Risa :)
>Glenn
>
>You say that you are using the normal method as described
>in "Keepers of the Light".
>
>Forget 'Keepers of Light ' for gum printing. It is an absolute disaster and
that
>is why you are having problems
>
>You are using so much pigment that the light is not getting to the
dichromate so
>it cannot tan the gum. That is why the pigment falls off. Mix a little
pigment ,
>about the size of a small pea, with your gum first on a plate so you can see
>the strength of the pigment as you spread it on the white surface. Mix 5 cc of
>gum with it and see how that looks when you spread it on the plate, and
then add
>5 cc of the dichromate.
>
> You made an even bigger mistake by using yellow which has such a high
>reflectivity that you have to use a lot of it to get any contrast, thus
blocking
>off the light even more.
>
>Despite what some people will tell you Arches is not a good paper for gum
>printing unless you size it first. Did you size it.
>
>Prepared gum goes off after a few days, it is better to use fresh each time.
>
>Let me know how you get on
>
>Terry King
>
>
>
>
>
>Any ideas, anybody?
>
>Glenn Cannon (glennon@netcom.com)
>http://www.newart.com/cannon
>
>