SUMMARIES

When applied to architectural drawings, the term photoreproduction means a copy from the original drawing that was produced using a process similar to the photographic process. In architectural archives, these prints, especially diazotype prints, are conservation staff's main preservation concern.

Diazotype reproductions usually show a reddish pink to orange discolouration. When an interleaving sheet of paper separates diazotype prints, discolouration is gradually transferred onto this paper. Furthermore, discolouration goes through the interleaving paper and reaches the next document. The results of this study show that this phenomenon is caused by the coupling agent used in the diazo process. Under alkaline oxidative conditions, this agent suffers polymerisation reactions leading to discolouration.