The Decay of Window Glass from the point of view of Lichenous Growths

JSGT 1924 V08 182-186

 What effect have the lichens on their support? Water must be retained by capillarity between the lichen and the glass, and this water must become surcharged with the carbon dioxide given out by the lichen during respiration; the glass is thus subjected to increased chemical action. The hyphae in contact with the substratum increase in number and in length, they become turgid or flaccid according to the amount of available water; the result is pressure on the surface of the substratum followed by incorporation of its disaggregated particles. Lichens thus accelerate the corrosion of window glass in much the same way that they aid the weathering of rocks.

Ethel Mellor