Re: How many gum layers (Re: ferri sesquichlorati)

[Halvor Bjørngård <halvor@ydl.net>]

And this... :-)

Kees

I did gum printing about 10 yrs ago and this is roughly the way I did it
then, except I used "normal" silver negs. Assumed since then that this is
the way one does gum. Did first come across the pigment adjustment method
recently & got a bit confused.

Pigment description is from : Wall, E. J., Jordan, F. I. Carroll, J. S. ed.
Photographic Facts and Formulas. Prentice­Hall and Amphoto. 1975. pp 313-14.

Both methods seems to give more or less straight curves, when you cut of the
top/dmax, 

(Found the rest of that book very interesting, the "pepper dusting on
process" has to be tried some day :-)

And the best description I have seen so far of the fresson process.)

I think I quietly back out of the rest of this debate :-)


On 10/25/06 12:51 AM, "Kees Brandenburg" <ctb@zeelandnet.nl> wrote:

> Hi Halvor,
> 
> For me the first method works best. I try to make negatives that fit
> carefully with the short scale of gum. The most important is to
> transfer all information in the original image to this negative
> (digital or analog the same). This does not mean information gets
> lost, it's only distributed à la gum. When printed with the first
> gumlayer and with the ideal printing time that gives  the first
> maximum shadow density I print for the transfer of all image
> information. When looking at this one layer gumprint all  image
> details shoulkd be there in all their delicacy. But this 'perfect'
> layer is still looking a bit transparant and  much to weak in shadows
> and midtones. Only the lightest part of the image is ok.
> 
> I then try to print extra layers with exactly the same gum/dichromat
> and pigment concentration (and sensitivity) while shortening printing
> time for each layer. This adds density in shadows and midtones and
> makes the straight part of the curve tilt upwards to get more
> contrast. A final extra punch can be added by a black or other dark
> layer with an extremely short printing time.
> 
> When printing too much layers sometimes density gets lost in the
> highlights by abrasion. That's the only moment when I sometimes print
> an extra layer with less pigment. But still the same gum/dichromat
> ratio.
> 
> kees
>