I don't recall saying I Triple size my paper.
Here's how it goes.
I use 300 BFK (great tooth to it - from what I hear this type of tooth is
necessary for anything, the gel, gum, dichromate, pigments to "stick") and
preshrink it twice in a short warm water bath, hanging it in oppositie
directions each time to dry (180degrees).
Then i give it 2 separate coatings of gelatin, again, hanging it 180 the
second time (for even shrinkage on both accounts)
Then i give formaldehyde (which I'd like to avoid in the future).
my gelatin mix is 29g to 1L of water
formaldehyde is 30cc to 1L of water
gum arabic is 14baume
sensitizer is 25g ammonium dichromate to 100cc of water
hardening/clearing is 25g potassium alum to 1L water
from here, I was taught (no books, just a photocopied list of recipes from
Jack Dale at York University and his 30-40 odd years experience with gum
printing to guide) to use an equal amount of gum arabic and amonium
dichromate solution (1:1) with my choice (lightest to darkest) of powdered
pigment (I have a huge list of wieghts for powdered pigments).
There was no need, with the preparation of paper as above, to size between
exposures.
I have read (Bea Nettles I think) that a launderers canned starch can be
used to "size" paper, and that this must be reapplied once for each
exposure, but please, don't misread what I've said, or point out this
horrendous error to me!
If the gum you were supplied with came "as is" i.e. straight from the jug
bought at the store, I don't think it will go bad in any quick amount of time.
How do the above recipes for mixture compare to everyone's working notes?
I'll repeat what I wrote in a private email to Glenn: I too have my
experience with gum printing in a very prepared, organized and established
environment - my university darkroom! In a month (when It's warm enough in
Toronto to try printing outside!), we shall see what challenges I come up
against! haha
ok.
um, that's all i can think of for now
Risa :)
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."
>
>What I was trying to do was to make a smaller "one shot dose" for
>each layer of color. I went to my notes from the 3 semesters worth of
>work and found that we were going with 9cc of gum to 3cc of
>aluminum dichromate, with 1/2 inch of black, or 1 1/2 inches of
>yellow, or 3/4 inch of red, or 1 inch of blue. It seemed to work
>well for single coated, monocolor prints.
>I'm trying to do a tri-color print. All the material I've read says
>that I have to start off with a yellow layer as the base layer. Isn't
>this the correct method?
>
>"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."
>
>No, I didn't. We've never had to size any paper in the class (except
>of course the salted paper, but then, that's part of the process!).
>The instructor told us that, after he'd done extensive research from
>the paper companies, that all of the papers we were using had already
>been gelatin sized, Arches cold press being one of the best for that!
>I had shown him in the various texts that sizing was recommended, but
>his comeback was that the papers had already been sized at the
>factory and that there was no need to do it again. And, after having
>several successes, we supposed him to be right.
>
>I got a couple of really informative notes from Risa (on this
>newsgroup) telling me she "triple sizes" her paper before attempting
>to do tri-color gum! I can't see the advantage, but I'm willing to
>try it too.
>
>"Prepared gum goes off after a few days, it is better to use fresh
>each time."
>
>I'm like you, I make sure that the complete mix, with sensitizer is
>prepared fresh each time I am printing. But as for the gum part of
>the equation, the same batch of it has just been used at the college
>last week, with great success by the students. They didn't seem to
>have any problems. And my bottle of gum came from that same stock!
>
>I just can't figure out why:
>
> 1. the gum never "set up" when I mixed the dichromate into it. (it
>never thickened)
> 2. the mask I made didn't work - all the coated areas of the paper
>recieved exposure prior to UV exposure, at least that's what I think
>happened, since all those areas remained either black (on the first
>test) or yellow (on the second test print).
> 3. nothing remained of any sort of image on the paper, just pigment
>stain. Perhaps I was going overboard on the pigment in my mix, but
>going on past experience, I didn't think so.
>
>
>If you have anything else you can tell me, or what kind of papers I
>may try for tri-color printing, please let me know. Thanks for all
>your help.
>
>Glenn
>glennon@netcom.com
>http://www.newart.com/cannon
>
>