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Re: dichromate and the plate
A copy of The Keepers of Light is within view of the computer and oddly
enough it opened to the Keiley print you refer to. Yes, that image does have
the look of a gum done the way I described below. But I doubt that you could
get that effect in gum using glycerine since there is no real developer with
gum aside from the solvent action of water.
Why not give the method I describe a try. Sizing is not needed because the
viscous pigmented gum sits on top of the dichromate undercoat and does not
get trapped in fiber. If the pigmented gum layer is puddled it will just
flake off since actinic light can't get through to adhere it to the paper.
But even when it is brushed on sheer, extra long exposure times are required
- at least twice as long as for a complete emulsion gum print. A browning of
dichromate in any areas not covered with pigmented gum will be evident. It
can be lightened with sodium bisulfite but a gray-blue-green version of it
will remain.
This method could be a way of painting with no light resist whatsoever. In
fact painting with complete gum emulsion, exposing and developing between
layers, enables a watercolorist to paint as if using oil paints since
underpainting can be fixed and is not disrupted by subsequent layers.
Sarah Van Keuren
>Katherine Thayer wrote:
> It occurs to me that the method you describe below may be the way to get
> an effect like glycerine-developed platinum (see Joseph Kelley's 1896
> print reproduced on page 52 of Keepers of the Light. Hope I'm not
> presuming too much to presume you own a copy or have one available
> nearby.) I tried briefly once to get that effect in gum, using
> glycerine, but without noticeable success.
>
>
>
> Sarah Van Keuren wrote:
>
>> I wonder if anyone nowadays, besides myself and my students, has tried
>> brushing ammonium dichromate onto paper and then applying pigmented
>> gum on top. The dichromate can be wet, dry or inbetween, each state
>> giving a different effect. This promotes a painterly approach since
>> different colors can be brushed on and blended together. I do this as
>> the step after producing prints in pure dichromate. Each student
>> chooses a color and brushes a patch of the pigmented gum onto the
>> large sheet of dichromated unsized BFK with some overlapping. I got
>> the idea from a 1910 issue of Photo Miniature lent to me about 20
>> years ago by Paul Cava of Philadelphia. I could tell more about this
>> way of working if anyone is interested.
>>
>> Sarah Van Keuren