The corrosive effects of degradation products from phenoplast, polystyrene, PVC and organic coatings are mentioned. Wood and its impregnants are also corrosive, especially to zinc, steel and lead. Formaldehyde from the coatings and formic and acetic acids from the wood are the most aggressive agents. The evolution of corrosive promoters may be hastened by additives or impurities in the materials. The thermal degradation of chloroprene and silicone rubbers at 100°C was investigated, in some detail, and the surface of gold and silver-coated copper was examined after exposure to the more aggressive products. Chloroprene rubber is more harmful, mainly due to the chlorine evolved. The most aggressive products from silicone rubber are formic acid, formaldehyde and hydrocarbon radicals. Other degradation products, and their interactions with the metals are noted. -- AATA