Four further pieces, Kriwet 1-4, are large-scale colour photograms of light sculptures by the Düsseldorf artist Ferdinand Kriwet. Using a mobile, precisely constructed darkroom, Goldbach took photograms on photographic paper from these circle-shaped text works made of neon tubes and coloured plexiglas, which have been in the RUB refectory since 1971 as 'Kunst am Bau'. On the one hand, these colour-intensive "mirror images" which appear like brandings, are a homage to Ferdinand Kriwet (1942-2018); on the other hand, Goldbach expresses his appreciation for the traditional technical process. The works can also be read as an ironic commentary on appropriation art.