|Michael Koerner, Escape, chemigram from wet-plate collodion positive, 2016|
Once you get past dipping and dunking - mind you, great works can be made that way, think of Alison Rossiter for starters - the most important concept you need to grasp in making a chemigram is that of the resist. A resist is something that blocks the action of developer or fixer. Tape, glue, friskets, varnish, wax, polish, clay, much of the food we eat, are all resists. Hard bulky objects can be resists too, a pair or scissors, a hammer, a bottlecap, as in the old photograms of the 1930s. As long as it sits squarely on the surface of the photo paper and doesn't let much chemistry in underneath, it qualifies.
But most resists are of the type that under the gradual, unrelenting action of chemistry will erode and dissolve. It may take just a few seconds, as with glue, it may take hours for certain varnishes, but eventually the resist is gone. This is a good thing, because by activating the mark-making potential inherent in the resist, erosion creates expressiveness. You will want expressiveness: it's the enabler that lets you say what you want to say with your art. If the resist is recalcitrant and doesn't want to come off it's quite okay to give it a nudge; what is less obvious is that it's also okay to leave it in place even through the final wash, and so incorporate it into your picture as if it were a cousin to hand-coloring or toning (see figure 7 in this post from November 2015). On the other hand, if you have an obdurate resist and don't remove it at all, you may want to treat it as a stencil, which is also a kind of resist, a decisive, permanent one, and it too may find a home in your toolkit. Again, refer to the old photograms.
Christina Z Anderson's tutorial article at alternativephotography.com shows a refreshing medley of resists that you will swoon over: cooking spray, toothpaste, hummus. In England, Daniel Berrangé's blog f/138 takes a systematic look at a number of resists and their governing strategies and is well worth consulting for the beginner.
What is totally unexpected about Michael Koerner's work, on display this month in the Alternative Process Competition at Soho Photo in New York, is the way he thinks about resists. A chemist by trade, his world is one of diffusivities, of phase states. Matter is considered not only spatially, by its location, or by its mass and density, but also thermodynamically, by what form it appears in at a given temperature, whether solid, liquid or gaseous. If you put yourself in this frame of mind it's a short jump, but a major insight, to view the solid-to-liquid transition as a porous barrier to the migration of fixer or developer.
In his system, wet-plate collodion, you first pour collodion over a metal plate, then you immerse the plate in a silver nitrate solution. An exchange reaction occurs and the bromide and iodide ions in the collodion form salts with silver. The plate is flashed on the enlarger and minuscule grains of silver begin to coalesce, though not yet manifestly visible. If you're making a chemigram you would have likely laid down a pattern of resist on the plate by now and then commenced applying your developer and fixer, in a sequence of your own invention, leading in due course to a completed chemigram. Koerner does it another way. He freezes the plate, which is still wet, and a very thin layer of ice forms on its surface. It is this new surface, ice, that becomes his canvas. He paints on it with fixer and developer, now with one, now with the other, and they attack the underlying plate and its emulsion in a slow ballet governed by rates of diffusion and of melting. As the process unfolds and chemistry seeps down, regions of fractalization appear, driven by forces which, though quantifiable and controllable in theory, in practice partake of a good measure of randomness.
In all of what are called positive wet-plate collodions, also known as tintypes, which is what we have here, the area where developer strikes the exposed emulsion appears white, not black as in conventional b&w photography, and the same inverted appearance holds for fixer. Thus in Escape, above, the white filigree on the far left represents developer activity. By using ice as a resist Koerner gains another advantage as well: he immobilizes the collodion-nitrate solution which otherwise would still be wet and displaceable, so that now he can focus his chemigramic interventions with a reasonable expectation of outcome. Those pustule-like structures seen best on the detail view are spots where the artist dropped in extra developer with a pipette, and could only have been done on a surface that was immobile.
Koerner gives us hints about his chemistry, which is not straightforward. For developers he favors those using metol or hydroquinone as reducing agents but has formulated a wide range of others, paying particular attention to the restrainers and accelerators present in the recipe, as these give him a tailor-made control over various aspects of an application, such as the amount of aggresiveness or submission needed. Astonishingly, he will often employ three or more developers on a single picture. Similarly for fixers, where a study of early literature has led him to some formulations well beyond, or prior to, the ammonium and sodium thiosulfate warhorses, in an effort to precisely calibrate the kind of black he wants.
This work is suggestive, mysterious, and thought-provoking. I urge you to explore his webpage at www.photoexperimentalist.com.