From: Dave Rose (cactuscowboy@attbi.com)
Date: 02/23/03-06:33:14 PM Z
Greetings from Big Wonderful Wyoming,
----- Original Message -----
From: "Christina Z. Anderson" <zphoto@montana.net>
To: "Alt Photo List" <alt-photo-process-l@sask.usask.ca>
Sent: Sunday, February 23, 2003 3:17 PM
Subject: gum printing
> Hi List,
> My usual barrage of questions for the week--but hey, at least I post
my
> test results, too, huh?
>
> Gum questions:
> 1. Which colors absolutely do not work? I have these notes: hooker's
> green (washes out), emerald green, and any chromium based colors. I've
loved
> the quinacridones in the past...moonglow by D Smith seemed to wash out
quite
> a bit but could've mixed it up wrong. Do all whites work OK and has anyone
> tried a white on a dark paper?
Most of the pigments I use are bought in powder form. Carbon Black from
Photographers Formulary is a favorite. Ivory or Bone Black is weaker and
warmer, but works well. I use the earth pigments a lot, Umbers and Siennas,
Indian Red, etc... They're an excellent choice for any gum printer.
Quinacridone is beautiful but weak, as you've noted. Cadmium reds and
yellows are effective but tend to be more opaque. Phthalocyanine blue and
green are excellent - great covering power and intense color. I've also had
great results with Cobalt blue (cobalt aluminate). I've never used white.
> 2. Do you use am di or pot di? I learned on am di and am wondering if it
> is worth it to buy some pot di. Webb/Reed say only use am di if you can't
> get pot di. Hirsch says use am di. Go figure. I just want to know what
> you guys use, and I do have the notes from the past about am di being
lower
> contrast/muddier but then those saying that isn't the case. Does it boil
> down to what you are used to?
I use both. Definitely buy some potassium dichromate and try it. Used as
saturated solutions, AD is faster and prints lower contrast than PD. PD is
my choice for most printing. On prints with multiple coatings/exposures
I'll often use both. PD is good for adding 'punch' into the shadows while a
strong exposure with AD (with weak gum/pigment) can produce beautifully
detailed highlights.
> 2a. If you diluted am di to the same percent as pot di would it be
> equivalent in speed?
I've never tried it. I use both at maximum strength.
> 3. What clearing agent do you use? I have come across sodium sulfite,
> sodium bisulfite/metabisulfite, potassium bisulfite, and sulfuric acid 1%
> solution. Does sodium sulfite truly do the trick so I don't have to
choke?
> the metabi literally gives me instant asthma.
Sodium metabisulfite. It is nasty stuff. Best used outdoors on a windy
day.
Certain pigments and chemicals used in gum printing are hazardous. It's a
good idea to have a complete file of MSDS sheets and follow all prudent
safety precautions.
> 4. Has anyone used lemon juice in the sensitizer to insolubilize it,
> decreasing exposure and giving better midtones? (Demachy, Photo-Aquatint,
> p. 39).
> 5. Dare I ask this, has Demachy's stain test been hashed out on this list
> already or is it worth mentioning? His book is from 1898, before Paul
> Anderson's 1911. Is it possible to talk this out civilly? If he has not
> been discussed, I can sum up his test and post it. Considering I've only
> been on the list 3 yr or so, you all could have been around this block
> before.
I'm not familiar with Demachy's "stain test". Please do give us more
information.
> 6. How many gummists are there? I know Judy, Dave, Katherine, Joe, but
who
> else isn't speaking up? Even part-timers?
> BTW, why I keep asking questions is I am in the starts of developing
a
> "user friendly" alt course as to how I would teach it if given the chance.
> I did it with experimental. Now I want to with alt. I've figured out I
> would "hook" the students first by doing easy enlarged negs (paper,
> imagesetter, ink jet), start them out with instant gratification cyanos,
> argyros, (then vdb, kalli, salt) to really get them hooked, then get into
> easy one coat gum with spray starch or acrylic sizing, then teach such
> things as better enlarged negs, better sizing, etc. afterward, before
> progressing into the more expensive platinum/palladium/zia. The biggest
> whines I hear is "it's so time consuming, I can't stand gelatin dripping
all
> over, I don't have any good large negs, etc." Kinda like the view
> camera--forget the zone stuff in the beginning, get them out there fooling
> around with the camera til they get seduced by the large neg and camera
> movements, and then go thru the complex stuff. They have to know "what's
in
> it for them" first. My philosophy for the day (of course, 10 processes in
> one semester is probably total overload).
> Chris
I wish you the best of success with your new alt-photo course.
Dave Rose
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