Re: Gum woes

> 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?

There is not a reason for you to do this. I start out with a much greater
saturation of color. I mix a 15ml tube of watercolor pigment into a 50ml
jar of gum arabic, I mean, the total of the two combined is 50ml, so my gum
would be 35ml. That is my stock pigment that I use. It is nice and liquid
and mixed that way, and therefore I never have to worry about lumps of tube
paint in my coating, giving uneven color. Then, at time of use I can vary
the amount of pigment in my mix by using 1/2 tsp of this stock to 1 1/2 gum,
or 1 1/2 tsp of this stock to 1/2 gum, always ending up with 2 tsp of the
two. I know my colors well enough now that I know with some I use a scant
tsp of the stock pigment, with others a hair over. Or, if I want to make a
very monochrome gum, then I really desaturate it. So my only reason is to
get the correct color intensity and not have uneven pigment mixing.

 ,> 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.

Sam and I differ in this one variable; my process I use was taught to me by
Sam--he is "da man" if you know what I mean. But I always size my paper
with brush sizing one side, one or two coats. That way my prints never
stain. If I get color that does not budge in the highlights, it is only
because I have not developed it long enough/overexposed it. Because I have
taken care of this problem with adequate sizing, I can be loosey goosey with
the rest of my approach. But, to each his own. By using highly pigmented
layers I get a full, bright gum print in 3 layers only.
Chris
Received on Mon May 9 18:23:09 2005