Possible Clues:

• Waterproof fabric
• Crude form of material is waterproof
• Muse, on reflection unwilling to supply waterproof material
• One initially unwilling to ring the Italian about waterproof material
• Reluctant to be removing coil first on canvas
• Waterproof material originally overused by the Italian clergy?
• Fabric good in rain and dreadful chill, too
• Bribe the clergy to provide waterproof material
• Canvas not to be used for watercolours!
• Canvas coated with type of linseed paint