From Calder
Calder lead highly recommend the application of a sealant when pointing joints between lead, brickwork and other masonry. Calder lead specially designed sealant is a one-part, neutral-cure, high-performance, silicon-based product specifically formulated for use with lead sheet and flashings. It is extremely durable, flexible and provides a much more efficient and reliable solution to using wet mortar, which historically doesnt perform well when exposed to temperature change. Shop an alternative product - EverBuild EverFlex Lead Mate Sealant