U of S | Mailing List Archive | alt-photo-process-l | Re: How many gum layers (Re: ferri sesquichlorati)

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

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.


On 24-okt-2006, at 11:05, Halvor Bjørngård wrote:

One last (maybe) gum question..

I have seen two approaches for building up the tone scale.. One is to use a
constant pigment concentration and on subsequent layers reduce the exposure

The other to use a constant exposure time but to increase pigment
concentration for each layer (which with my test reduces sensitivity

Is one method more usual than the other, I originally only knew the first
one.., Is one method best, or is this just a matter of purpose ... Comments
any one ?