Burnt Sand Mastic - The Original Mastic for Timber Windows & Doors
Burnt Sand Mastic: Supplied in two parts. Burnt Sand + Oil-Driers. Used to form joints between timber window and door frames and masonry or rendered masonry, traditional burnt sand mastic has been in use for at least 200 years. It hardens slowly but remains sufficiently flexible for the purpose. It adheres tenaciously to most surfaces.
It is made by roasting sand on a hot plate or in a small kiln and was originally mixed with oils, lead based driers1 and crushed chalk. However for many years now, alternative natural driers have replaced the lead products.
Mixing
The Burnt sand mastic is combined with a mixture of oils and driers (supplied with the sand mastic) on a clean surface, Mix thoroughly using the minimum amount of oil. (If the mix is over wet, let it stand in a warm place for a few hours to stiffen up then remix vigorously before use)
Once mixed with Oil - Driers, mastic will harden. Mix only that which can be used in a few hours.
Application.
Before pointing ensure that all wide gaps between the frames and the masonry are tightly packed with well haired lime mortar (MM2LPL) that has been allowed to cure and harden. (This was the original material used to bed window frames) In some circumstances inert filler boards of suitable packing can be used. Keep the joints slightly recessed 4-5mm.
Take a small painters Fitch and apply a light primer coat of the supplied Oil - dryers to the frame and the adjoining masonry surface, making sure that the line of the proposed mastic joint is maintained. Do not over oil surfaces.
Working with a Mastic Box or a small hawk and a proprietary mastic trowel press the mastic firmly into the angle of the frame / jamb and filling from the bottom up, forming the mastic joint to a neat 45 degree angle. Keep tools wiped with an oiled cloth during the application.
After forming the angle, starting from a corner, press a clean oiled mastic trowel tightly against the face of the timber frame and masonry jamb and carefully press and draw the trowel to create a neat regular fillet. Clean away any excess mastic and wipe the finished timber edges on completion.
For mastic to sills, ensure the mastic does not bridge any drips and is left recessed behind the drip check.
Mastic should not be over painted.
Mastic fillets should be neat 20 - 25mm across the diagonal face, mastic should not be used to make up damaged arises or defective renders, these deficiencies should be repaired properly before mastic work commences. We supply stone repair materials and other lime products for repairing renders
| Traditional Burnt Sand Mastic | ||
|---|---|---|
| Product Code | Price Per Tub / Burnt Sand &Oil- Driers (2 part) | Oil - Drier If sold Separately 2.5 / 1.25 Litre bottle |
| MMBSM ( 10 Litre tub) | £18.99 | - |
| MMBSM ( 5 Litre tub) | £11.00 | - |
| MMMOD ( 10 Litre tub) | - | £10.50 |
| MMMOD ( 5 Litre tub) | - | £6.50 |
| MMBSM (Custom Coloured) |
£24.00 | - |
1Lead driers are not used in our Burnt Sand Mastic.
We supply trowels for the application of Burnt Sand Mastic. Please click here for details and prices.
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