Womersley's Burnt Sand Mastic is ideal for pointing around windows and doors (timber or metal). Burnt sand mastic adheres tenaciously to most surfaces and has been used for over 200 years in building construction and renovation. At Womersley’s we follow the traditional method of preparation by roasting fine silver sand and supplying with British Wax linseed oil which has been double boiled with rosin driers added. Designed to harden slowly but remain flexible, Burnt Sand Mastic efficiently reduces the risk of cracking when forming joints