Printing a layer (or more) of gum bichromate over a finished platinum or
palladium print was an early 20th century pictorialist strategy. The idea
was to get the delicate highlight definition of platinum/palladium while
beefing up the shadow density or "body" of the pl/pd with a layer of gum.
Note by the way that a pictorialist goal was generally to *subdue* shadow
Various dictionaries of the period mention the topic; Paul Anderson has a
chapter on it in "Technique of Pictorialist Photography", but it is almost
entirely lacking the kind of details that would interest us, dwelling
rather on issues like calibrating skin tone with the linen of the sitter's
collar. And no mention of preshrinking paper before doing the platinum
print so the gum coat would register. In general, a lack of register in
the second coat that would drive us wild didn't seem to, so-to-speak,
register with the pictorialists.
Their paper may have shrunk less but soft focus was anyway style & goal.
As Anderson put it, "faulty outlines may often be remedied by a few
touches of a pencil on the finished print." Got that?
Stieglitz, also Steichen, did gum over platinum (Moonrise or some sky
phenomenon over Mamaroneck, The Flat Iron Building, etc.), but I could
never figure out how they got color in the otherwise blank skies -- maybe
they printed the gum with the positive.(?)
As for cyanotype on ceramic -- guess a flat surface is planned,
otherwise some ingenious way of fastening negative to curves. A student
of mine spent most of a semester attempting this; all trials turned
beige on firing, tho maybe a different glaze/clay/temperature would have
done otherwise. I suspect, though that for photos on clay a dust-on or
bichromate process using underglaze pigment would be the best bet if the
work is to be fired.
To keep the cyanotype blue, you can print on bisque ware and NOT
refire, tho there may be continuing seepage from the clay which would
affect the color over time.
Kent Wade's sadly out-of-print book, Alternative Photography (or
Alternative Photographic Processes?), is the best source I've seen for
photo on ceramics and other craft media. I have, unfortunately, NEVER seen
this book for sale second-hand. I suspect that to get one you have to hang
out at the hospital and when an owner dies rush over to their place and