Sunday, July 18, 2010

Resistive notes (1)

Collins, 071210CH-1, detail

In the simplest chemigrams (the word 'simple' is deceptive, since these are often some of the most powerful works), form, body and color are applied in a direct way by merely dipping and dunking the photopaper in fixer or developer. To get more complex effects, one usually employs a resist of some sort. Resists are materials that block or delay the action of chemistry on a region of paper until a later moment, when surrounding areas will have already transformed away from their original state. When the resist is finally removed or erodes by degradation, chemical action can now begin in these areas as well, which because they have 'fallen behind' the others, will have a contrasted appearance. This is the source of much of the imagery in chemigrams.

Resistive materials are many and varied, as are the strategies for using them. What I like to call 'soft resists' are materials whose lifespan on the photopaper is quite limited, counted in seconds to a minute or so. Materials like white glue (polyvinyl acetate emulsion), corn syrup or other food products, tape, chewing gum, and clay are found in this category. The list extends, and among chemigramists it is a matter of some joy to identify new candidates for inclusion. Ideally, a resist should not totally resist, but instead should have a little give around its edges, so that as the resist begins ever so slightly to lift off, the paper beneath is quietly and progressively changed - and this may continue for a while - before the big moment when all or most of the resist at last raises itself and sloughs off. This creates drama and interest. In technical terms, what is left behind is a sequence of Mackie lines, or tidal marks of erosive history. They can be seen in the illustrations accompanying Rich's post of June 27, or better yet, in much of the work of the great Belgian artist, Pierre Cordier.

If we have soft resists, we must also have hard resists. Hard resists are materials that endure several orders of magnitude longer before leaving the photopaper, sometimes up to an hour. Several are known. Perhaps the most effective and reliable (as far as my knowledge allows) is mineral spirits-based synthetic varnish, and there are a number of them to choose from, some good, some not so good for various reasons. Some in fact inhibit others, if used on the same piece of photopaper.

By way of launching the discussion, here is an example of W&N ConserveArt varnish (green arrow) having thickened its activity to the point of quenching the normal spread of Liquitex Soluvar (red arrow), when the two varnishes were mixed together. The illustration is at 40 minutes of history. The Soluvar effects began to be evident at around 9 minutes along lines of incision (another story), while at that time there was no sign of ConserveArt activity. Then, insidiously, cracks appeared in the non-incised areas, while Soluvar effects seemed delayed. The cracks soon became larger and formed tilings, with tiny, characteristic Mackie lines. Comparison with other experiments led to the conclusion that this was ConserveArt activity. By now Soluvar activity had ceased altogether.

In notes to follow I will explore these and related topics, share observations from my studio, and try to find a basis to understand the mechanisms involved. For with understanding comes wisdom and with wisdom, art. Or something like that.

No comments:

Post a Comment