Foxing caused by Fungi: twenty-five years of study

The author provides an overview of his many years of research investigating stains on paper, called “foxing”. Foxing, in the authorʹs experience is caused by fungi. The development of a specialized petri dish technique (Aw 0.94 or 0.84, and 25°C) as a culturing method for microorganisms has enabled the isolation and culturing of fungi that can produce the foxing effect. The foxing effect has also been found to occur on materials other than paper, e.g., silk. Therefore, it may be concluded that when the optimum environment exists, there is a possibility for foxing to appear on paper and other materials.