Rust coloured spots which occur on paper resulting from oxidation of both organic and iron impurities left behind during the paper making process. Only when these impurities exist in the paper, given exposure to the right humidity and temperature factors, will foxing occur. This process is intrinsic to the paper; some paper will never have the rusty, brown, yellow spots known as foxing.
Dutch: Roestvlekken, weervlekken
Italian: Arrossature, rifioriture
Spanish: Puntos de oxido
Swedish: Lagerfläckad, brunfläckad, "foxed"