Re: dark gums

["Gordon J. Holtslander" <gordon.holtslander@usask.ca>]

Hi:  

I wonder if carbon printing, or oil print might be better capable of producing 
very dark pigmented prints than gum.  (Gord prepares to put on his flame 
proof suite :) )

I haven't done carbon printing in a long time.  One would have to buy or make 
the carbon tissue, and do the transfers - which is a lot more work than 
prepping and processing single layer gum print.  But a gum print would likely 
have to printed in many layers - at least the gum prints that I have done.

Can any of the gum wizards get really dense (dark) prints in a single coat?

The prep involved in doing carbon is much more than gum - but the print could 
be done in one step.  Gum likely would require many printings - thought this 
could be used to your advantage - using slightly different pigments.

The other alternative could be oil prints - the image is created with a 
lithography ink.  

Oil prints - you coat paper with a thick coating of gelatin, let it dry.  You 
sensitize it - I use a brushed on spirit sensitizer - ammonium dichromate in 
alcohol - this dries within 10-15 mintues.  Expose this under a negative - it 
selectively hardens the gelatin in relation to the negative. The print is 
soaked to remove the dichromate and left to dry.  

To ink the print - it is again soaked in water - the temperature and the 
duration of the soak affect how the print will ink.(I soak my print for 1/2 
hour at 20 C) The print is then drained and the surface blotted dry (I use a 
paper towel).  The hardened gelatin will not hold water, the unhardened 
gelatin will hold water.  A lithography ink is then brushed,dabbed onto the 
print - it will stick to the dry hardened gelatin, and be repelled by the wet 
unhardened gelatin.  The image gradually appears under a brush as you ink the 
print.

 I've been able to get some very dense oil prints using a black ink.  

You would have to learn the inking technique and deal with cleaning oil based 
media.  The prep time for an oil print is fairly quick though, but inking the 
print can take a significant amount of tine,  If you try it  I would recomend 
buying a litho ink - I've been experimenting with creating my own oil media, 
but haven't managed to get anything that works as well as litho ink.  Litho 
ink can be purchased though Graphic Chemical & Ink 
http://www.graphicchemical.com/

I would see if you can do what you want with gum - if not try carbon or oil :)

Gord

On Wednesday 17 January 2007 8:51 am, ilana wrote:
> Hi all,
> I am relatively new to gum printing. My goal is to make dark [brown, black,
> deep blue] monochromatic gum prints. [Some may suggest I use a different
> process, I realize that]. I'm looking for advice/support [if this had been
> talked about in another thread, please direct me] on preparing the
> negatives--in terms of density, contrast and the ink/gum combo to get
> richness and detail. I know it is a matter of testing things but I thought
> any extra advice I could get would be useful.
>
> Thank you,
> ilana swerdlin

-- 
Gordon J. Holtslander		Dept. of Biology
gordon.holtslander@usask.ca	University of Saskatchewan
Tel 306 966-4433		112 Science Place
Fax 306 966-4462		Saskatoon SK., CANADA
homepage.usask.ca~gjh289		S7N 5E2