Burnt sand mastic

[David H-S]

Has anyone worked with a sand, resin and linseed oil based mastic for repairing the gaps between broken stonework and window frames? It is intended for older buildings where one wants to repair large gaps between stone mullions and cills and the window joinery and where looks are important.

It provides a much better looking repair against old stone than any modern mastic from a tube; it remains a bit more flexible than any cement based product.

Womersleys of Heckmondwike is one supplier of the stuff.

am slowly learning by trying how to mix it, how much linseed oil to use and how it behaves and sets.

I should be interested to hear from anyone who has used it and has tips to offer.

David H-S

[Mary Fisher]

When we pointed our house we used mastic sand - used in foundries (including the one where Spouse worked). The sand was already coated with mastic, as I understand it. We obtained boiled linseed oil and mixed it in small quantities until it felt right and was easily workable.

True on both counts. We used red mastic sand because we were pointing brick, it was far more harmonious than the stark contrasting compo usually used on brickwork.

It takes a long time to set - far longer than it will take you to use it. Once set it's set for a lifetime I'd say - ours is still sound after forty years.

I'd say go ahead, it's very satisfying to use and gives a great finish. The extra expense is worth it. It feels good on the trowel and doesn't snot. We had very happy times doing that pointing.

Mary