The German filmmaking collective Schmelzdahin, made up of Jochen Lempert, Jochen Muller, and Jurgen Reble, conducted a number of experiments in unconventional film processing over twenty short films made between 1983 and 1989. The group was particularly interested in provoking bacterial decay in order to purposefully damage film stock. Reble buried a super-8 print of an action movie in a corner of his yard, leaving it there for the duration of the summer. After digging up the film, he found that, "The colors remained very pure and intense, but had departed from their previous form. Indeed, they were laying themselves down upon the old action film to form veritable mosaics of color, remarkably like the stained glass of church windows."
When he attempted to make a print of the decayed film, however, the projector lamp of the optical printer melted the film beyond saving. The group also made films by "buffing, punching, carving, chiseling, scraping," and by taking "sewing machines, knives, hammers, a soldering iron, etc." to the material in what amounted to an extended study of the limits of subjecting the film to stress and trying to see what could be projected. In Stadt in flammen (City in Flames, 1984), the filmmakers buried their material in leaves. Bacteria separated the color in the film to the point where the images they shot were largely lost or obscured. A hospital remains one recognizable element, and the film's soundtrack is a sickly mix of coughing and stuttering, as if the person heard is breaking down in a manner similar to the film we see. Another project saw the group hanging photographed and found super-8 footage from trees, where the stock was exposed to sunlight for varying number of months. Wind and rain tore the film, while the sun bleached the emulsion of its reds and blues.
Reble began digitizing his chemically treated 16mm films from the 1990s so as to reorder their imagery. In the process, Reble discovered new patterns in the older materials. For Materia Obscura (2009), he revisited his 1995 film Instabile Materie. The original film was composed of hand-processed passages of chemically treated filmstrips. By running these "chemograms," as he calls them, through computer-editing software, Reble was able to slow down the passage of imagery and allow viewers a closer look at the natural changes occurring on the original film's emulsion