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What is Burnt Sand Mastic?

Posted by Ian, Celtic Sustainables on

Burnt sand mastic is a traditional and arguably superior method of sealing the joints between wooden door and window frames and the surrounding masonry. 

The mastic fillet should be applied between the timber and the masonry at an angle. Any damage to the stonework should be repaired first with a mortar or masonry filler

Traditionally sand which has been baked to remove any moisture was mixed with lead based binder and crushed chalk. For safety reasons natural driers are now used instead of the lead. The modern, safer option consists of 2 parts, burnt sand and linseed oil. The two are mixed together only when they are needed as the setting process can be quite quick. It is advisable to mix up enough mastic for a couple of hours work and no more. The finished product is a waterproof mastic that retains a small amount of flexibility. The Mastic doesn’t require painting, but  If you do want to paint it, linseed oil paint is recommended.

Burnt Sand Mastic (10 Litres)