Démossions

Démossions is a term used in some discussions of historic preservation and landscape maintenance to describe the deliberate removal of moss from stone and masonry surfaces. While not an established technical term in conservation practice, it appears in bilingual French-English discussions as a neologism to define the action or process of de-mossing, particularly on exterior façades, monuments, and traditional pavements.

The word combines the French prefix dé- (indicating removal or negation) with moss, the common name for bryophytes, and the noun-forming suffix -ions, yielding a nominalized form for the act of removing moss. It is sometimes treated as a calque of the English “demossing” but remains largely informal and theoretical.

In inscriptions and conservation guidelines, proponents of démossions emphasize the maintenance of historical legibility and structural integrity when moss and accumulation retain moisture or promote biological growth that harms porous stone. Critics argue that moss can play a protective or ecological role, and that aggressive removal may damage stone or erase patina and microhabitats; management is typically site-specific and based on risk assessment.

Practices associated with démossions commonly include non-abrasive cleaning, careful brushing, poultices, and, where necessary, chemical treatments, all chosen to minimize environmental impact and preserve historic material. The term remains largely informal and its use is more common in discussion forums and preliminary project briefs than in formal conservation documentation.