Re: (Gum) Multi prints???

Terry et all,

I was going to try arguing with you about the numbers you are giving us but
I changed my mind because to me the importance of the density range, being
just a difference between two densities, hi and lo, is almost irrelevant
compared to the path (curve) between these same two numbers.

I think we can all agree that gum printing as a wide envelope or in other
words gum printing gives the "printer" a lot of lattidude. Within certain
limits of which I have no idea of as of now, the printer can use almost any
combinations of ingredients he or she wants and get "interesting" results. I
use this word "interesting" because artistically it can mean almost
anything.

I can visualise quite easily what Tom said, the photons can transform as
much gum as they want on the surface of the emultion but if they don't get
deep enough to insolubilise gum at the paper interface, the gum wont adhere
firmly enough to the paper and it will simply wash of at development time. I
don't know the exact numbers but at some point the amount of the pigment
particules will be so great that no light will get to the paper interface
and this "amount" will vary from pigment to pigment obviously.

I understand that the pigment we use, in the large sense of the word, have
the "net effect" of increasing the density of the negative. Lets not forget
that we see as a highly translucent yellow pigment may very well be quite
opaque in the UV range. From the test I've made, this "added" density seems
to bring the exposure values right in the most linear and most interesting
part of the gum emultion response curve.

One last thing I could add, I not convinced that using a single exposure
with a negative of a relatively low density range (0.7-0.9) automatically
mean it is "not going to produce a very exciting image" to use your own
words. If one is using a pigment that is just "right", meaning optimal for
both the UV and the visual spectrum it is quite reasonable to think, that
with the Dmax and gradation we can get from this mix, we can very well
produce an exiting image, I wouldn't be surprise if there where quite a few
pigment that could be used in single coat prints. As I said above, the gum
process as a wide envelope or a wide gamut if you prefer, I would be the one
to seek what those limits are and update the maps accordingly instead of
being satisfied with the already explored territory.

Yves
PS I live near Montreal way up there in Canada.

----- Original Message -----
From: TERRYAKING@aol.com
To: alt-photo-process-l@sask.usask.ca
Sent: Wednesday, December 14, 2005 3:55 AM
Subject: Re: (Gum) Multi prints???

In a message dated 14/12/2005 02:40:42 GMT Standard Time,
cactuscowboy@bresnan.net writes:
I've had best results printing gum with negatives that would be "perfect"
for use with Grade 2 silver gelatin paper. With my methods and printing
preferences, a negative with 0.7 density range would be a bit flat, but
certainly not unusable. Also consider whether Potassium or Ammonium
Dichromate is being used, that will make a noticeable difference.

Dave Rose
Powell, Wyoming

The point is that multiprinting enables one to build the contrast. Given
this control, the difference between the ideal gum negative with a density
of 0.7, and the 0.9 negative which is 'ideal' for silver gelatine, is
minimal. I usually use negatives with a density of around 0.9.

The multiprinting principle works well with other processes such as platinum
and classic cyanotype.

The cyanotype rex gives greater flexibility.

Terry

Terry King FRPS

RPS Historical Group (Chairman)

www.hands-on-pictures.com/

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Received on Wed Dec 14 08:30:50 2005