A heat mediated photogram

Heat is, as light, an electromagnetic wave. Light is the mediator of photography, heat is the mediator of many sculptural processesincluding melting, burning and other chemical transformations that happen inside a ceramic kiln fring.

In the ancient ceramic technique of Raku a pot is fred until it reaches red hot temperatures (about 1000oC), it is then removed from the kiln and exposed to organic material. In one particular variation of Raku an individual object (the referent) - say a feather or lock of hair - is allowed to touch onto the pot’s hot surface. The heat causes the object to immediately ignite and the burning carbon afects the chemistry of the clay on the pot’s surface, resulting in a permanent black ‘print’ of the object’s shape.

The image produced is of the same order as a photogram (a cameraless photographic technique in which an object is placed directly onto light-sensitive paper and exposed to create a silhouette). Such processes produce a simple outline of the object (a ‘reduction’ - one of Barthes’ original three indexical operations). The light-mediated photogram does this in a ‘negative’ way - in that the outline is produced in the area of the paper where the light has been blocked out by the object. In the heat-mediated process the image is a positive one (the mark comes from the carbon in the object burning onto the ceramic surface). The Raku-gram is then, arguably, even more direct and even more ‘purely physical’ than its photographic equivalent.

Such a process could also be compared to making a print of an object by coating it in ink and pressing it onto a piece of paper. Ink-printing must be mediated by another material (the ink), whereas in the Raku process the actual materiality of the referent (the carbon inside the molecules it is made of) are what mediates the mark making. The Rakugram is more physically direct than an inkprint or photogram, and also more materially direct. A material as well as a visual index.