Stained and Painted Glass

An additional note on lead cames in a modem context is important. Lead is now extmded into cames by precisely measured machinery that can cut down greatly on the amount of lead used, and hence on the weight of the cames. Furthermore, addition of certain metals or metalloids, such as antimony, to the lead stmcture serves to strengthen the lead and give it a life exposed to the weather for perhaps many centuries. Stained glass windows can be further protected by the preventive conservation technique of protective isothermal glazing. 

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Fig. 4.1 Stained and Painted Glass (ca. 1200 CE) in the Narthex of Cartmel Priory, Cumbria, England. Photograph by M. V. Oma...

PEG, being well above its glass transition temperature at room temperature, can act as a solvent for inks and paint (Hey et al., 1960) or a plasticizer for polymers, e.g. PVAC, CN or colophony (Powell, 1980). It may cause stress cracking of moulded thermoplastics such as PE. It does not appear to attack beeswax or gelatine. The presence and quantity of PEG in a solution or thin section can be assessed by colour staining (Hoffmann, 1983 Bilz et al., 1999), but distribution within an object is frequently assessed by extracting the PEG from a core and using instrumental analysis to quantify the concentration (Hoffmann, 1989). 

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