(Special eco-bonus: gum bichromate prints are "developed" using only water. No developer, no stop, no fixer, no toner. You listening?)
That the reader has basic skills with PhotoShop, Gimp or some other photo editing software is assumed. The purpose of this document is to explain in almost painful detail exclusively how to perform the printing portion of the process, although rudimentary information is provided, since it is vital in explaining portions of the methods used.
That the reader is skilled in working with potentially dangerous chemicals and understands the risks associated with such activities is also assumed. Warning: dichromates are poisonous and should not be ingested. Raw dichromate crystals look like orange-colored sugar but can be lethal. Be smart.
This is the starting image of carabiners used for the demonstration: the raw image with the exception of its being scaled to 1000 pixels on the long side @ 72dpi. No other changes have been made. Total eye candy.
For the camera technoids: original 3Kx2K image produced using Nikon D50 with 100mm Sigma macro @ f8 and Nikon SB-60 flash (-1 EV) with hood on Bogen 3021/3047 combination, but that's only so much nonsense.
(Yeah, yeah...so what's the deal with the process being called a bIchromate but the photoreactive chemical being used is a dichromate? At some point during its golden age, major discoveries were made in molecular chemistry, leading to a sort of unification amongst international chemistry unions regarding naming conventions. Chemically, bichromates were dead in favor of the much zippier dichromate. Photographers decided simply to ignore the chemical name change and stick with the deeply rooted bichromate. (Trivia! Get your trivia heeyuh!)
Step 1: Materials required
To create color separation negatives, acquire these items:
- a computer and PhotoShop, Gimp (go open source) or other photo editing software
- a digital image of reasonable resolution to create a print of desired size
- transparency film
- photo printer
To create light sensitive coating, commandeer this gear:
- liquid water color pigment in tubes
- saturated solution of dichromate (ammonium, sodium or potassium): 3 x 5ml
- 3:1 cut gum Arabic solution: 3 x 5ml
- mortar and pestle
To create final print, jack this stash:
- watercolor paper
- reasonable quality paintbrush that won't streak (quality hake brushes are quite inexpensive)
- masking tape
- print frame This does not have to be a deal breaker. A crude print frame can be made by hinging two thick sheets of glass together to sandwich the paper/negative combination. A local glass shop should be able to supply two 11x14" sheets of non-UV glass with polished edges for maybe $15 An even less expensive method that is limiting in that it permits printing with overhead lighting only is just using one pane of glass atop some flat backing. Be creative, O Pioneer.
- light source or our star, Sol
- photo trays
A work table...an Ansel Adams print of Canyon de Chelly - 26 x 20.
A 16x20 contact print print frame. This is a Bostick and Sullivan maple model. Unbeatable product.
Two sheets of *gelatin-sized* 11x14 sheets Lenox 100 paper
Color separation negatives (10" x 7" approx.)
Mortar and pestle
Gum Arabic (250ml 3:1 cut)
Ammonium dichromate (100ml of saturated sol.)
2" Hake brush
(Off camera: three 11x14" trays and a pencil that was going to make make a later appearance but ended up on the cutting room floor.)