From Calder
In damp or wet weather conditions, new Calder lead can on occasion develop an uneven powdery white, non-adherent coating of carbonate. This can be washed off by rainfall and cause staining on materials below. To counteract this, Calder developed patination oil to prevent this from occurring. Key Features: 125ml 10 dosing bottles per box Shop an alternative product - Everbuild Lead Mate Patination Oil