Re: Gum woes

Hello Scott,

Interesting to hear of your experience being a color blind photographer. Is
it frustrating at times?

You can experiment with various ratios in your gum emulsion mix to obtain
different effects.

Here's a quick and brief summary of how ratios effect the final result.

More pigment: greater color saturation, more tendency to stain.
Less pigment: subtle color, weaker effect, better for multiple printing.
More gum, less sensitizer: prone to flaking, slower printing speed,
contrasty.
Less gum, more sensitizer: faster printing speed, less contrast.

As noted by others, the type of paper used and sizing will make a big
difference. FWIW, I've had good results using Rives BFK paper treated with
a gelatin size hardened in formaldehyde.

For sizing, I soak the paper in gelatin solution for about five minutes and
then draw it at an oblique angle between two very smooth wooden dowels
(finished with polyurethane). This strips the excess gelatin off the paper,
leaving a thin coat behind. After treating the paper twice in this manner,
I soak it in a formaldehyde solution and dry it. I've never brushed on
sizing so I can't say that my method is better.

A saturated potassium dichromate sensitizer solution will print slower but
produce higher contrast than a saturated ammonium dichromate solution. Use
both to fully exploit the process.

The real 'magic' in gum printing comes when you have control over the
process and can manipulate the variables during multiple printings to create
effects that are unattainable with conventional photo processes.

Best regards,
Dave Rose
Powell, Wyoming

Gum & Cyanotype/Gum prints at:
http://www.alternativephotography.com/artists/dave_rose.html

----- Original Message -----
From: "Scott Wainer" <swphoto@verizon.net>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Monday, May 09, 2005 5:13 PM
Subject: Re: Gum woes

> Hi Chris,
>
> > Scott, I should make clear that when I use a formula of 1 gum/pigment, 1
> > gum, 1 1/2 water, and 1/2 am di saturated, that I am always using a 1:1
> gum
> > to di ratio; the water is just diluting the strength of my am di--in
other
> > words, 2 tsp of gum, 2 tsp of am di solution makes up my mix. It's
> important
> > to have it liquid enough to spread easily, but not so liquid it absorbs
> into
> > the paper like water.
>
> So basically this would cut the sensitivity of the emulsion to about 1/4
> speed but the visosity of the emulsion stays the same? Wouldn't that also
> cut the amount of pigment (to 1/4 strength) that was applied making it a
> thinner coat? If I normally use 4ml of sensitizer (2ml of gum/pigment and
> 2ml of dichromate) to coat a 5x7 image, using the above ratio I would have
> 1/2ml gum/pigment + 1/2ml gum + 1-1/2ml water + 1/2ml dichromate; which is
> still 4ml for a 5x7 image. To get the same intensity it seems to me I
would
> have to apply 4 coats. Is there a reason to do this? I seem to remember
> reading somewhere that shadow (?) detail can be built up through several
> coats, is this what I would be doing? Could I use 2ml gum/pigment +
1-1/2ml
> water + 1/2 ml dichromate to get the same effect?
>
> > Scott, I have used Lenox for gum, and with correct sizing it worked OK,
> but
> > was a more absorbent paper and a less dimensionally stable paper than
> > Fabriano. I use nothing but Fabriano now. It does not budge much when
> > shrinking and developing.
>
> Yes, I think the paper was part of the problem. I brush sized with out
> shrinking it first and found that after the first coat/development it
shrunk
> slightly which made negative alignment a problem. I had some Lenox that
had
> been shrunk but not sized and it just soaked up the sensitizer and stained
> completely - the pigment didn't wash out of the unexposed areas. So I
guess
> the Lenox is strictly for other processes since I haven't had any problems
> there.
>
>
> > I truly think a lot of the gum problem comes in the sizing. If you are
> > using printmaking papers, traditionally they are not sized as heavily as
> > others because they have to accept the inks. In printmaking
(silkscreen,
> > intaglio, etc) I do use Lenox because of its cheapness, but I notice it
is
> > less absorbent than, say, an Arches Cover, so I know it has more sizing
> than
> > other printmaking papers, but it just isn't as well sized nor as sturdy
a
> > paper as Fabriano.
>
> I was thinking about sizing by soaking and squeeging by rolling the paper
> face up on glass with a piece of stiff pvc pipe. If I used that method
with
> a 3% gelatin size + hardener added (glyaxol or chrome alum) do you think
> that would be better than brush sizing only one side? I'm not concerned
with
> the back of the print so it wouldn't matter much of the back wasn't really
> smooth would it? Since I plan on using Fabriano Uno and Arches Aquarelle
for
> 3 color gums, should I size them in addition to shrinking them? I saw some
> of Sam Wang's images on the Unblinkingeye website and liked the look of
gum
> over cyanotype. Reading his article, I noticed that he said he doesn't
size
> his papers when doing gum over cyanotype.
>
>
> > I also have to mention that I use intensely colored layers, and with a
> good
> > size, staining does not happen. I only back off with my color strength
> when
> > I feel it is too chromatically brilliant for my subject matter, never
> > because of stain. And that is with only a 3 layer print. This, again,
> true
> > of Fabriano Artistico HPEW (not Rives BFK and others).
> > (Can you tell I am out of school or what???? I mordancaged til 1 AM
last
> > night!!! And then watched a movie til 3 AM!!)
>
> As I have said before, I am extremely colorblind - colors look dull and
> don't vibrate as non-colorblind people have told me they do. With that in
> mind, I once took an oil painting class with a professor that does copy
work
> at the Smithsonian and couldn't figure out why he always put his
sunglasses
> on before looking at my paintings. When I asked him about it he said they
> made his eyes hurt because I used pigments straight out of the tube. I had
a
> tendency to use colors that clashed since I couldn't see what they did. I
> also thought it funny that my color photography teacher gave up on trying
to
> teach me color balance and told me to take my images as far out of balance
> as I could through cross processing and temperature adjustment. Have you
> ever seen a neon natural landscape? As for being out of school, isn't it
> great? I was on vacation from work last week and spent 10-12 hours a day
in
> the darkroom the whole time. It was wonderful.
>
> Regards, Scott
>
> swphoto@verizon.net
>
>
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Received on Mon May 9 20:17:25 2005