This brief article summarizes an 87-page publication entitled * 2Investigation of protection of medieval windows*1, by H. Patzelt, G. Tünker, and H. Scholze, of the Fraunhofer-Institut für Silikatforschung in Würzburg (Federal Republic of Germany). Samples of glass with high potassium and calcium contents were produced to replicate old glass and test the effect of weathering during measurable exposure times. Experimental conditions observed are outlined; the results obtained did reproduce natural damage; reversible protective coatings were then tested: they are based on a heteropolysiloxane combined with acrylates to yield water-repellent layers of a lacquer-like substance further described in the text. -- AATA