Four panels of sample bars processed differently: not processed, rough, rusted and polished. Each heat of steel (330 tonnes) in the bassic oxygen steel plant of Tata Steel IJmuiden is made, one takes a final sample to determine the analysis of the steel. Of the final sample the operator cut off the inflow bar. Each bar is unique and belongs to a certain heat. These bars, which would otherwise be thrown away, Nico with his colleagues collected from February to August 2011. 3491 bars of final samples of 3491 heats ( per 24 ours there are made 65 heats on average). The artwork is created of these bars.