Ironstone Burnt Sand Mastic
Traditional breathable mastic ideal for pointing around wooden / metal windows and doors. Burnt sand mastic adheres tenaciously to most surfaces and has been used for over 200 years in building construction and renovation. Manufactured from roasted fine silver sand and British Wax linseed oil with rosin drier added. Hardens slowly and remains flexible.
Description
10L, including 2L of double boiled linseed oil. Traditional breathable mastic ideal for pointing around windows and doors.
Coverage
Approx' 1Kg at 10m to a 5mm joint.
Preparation
Before pointing ensure that all wide gaps between the frames and the masonry are tightly packed with well haired lime mortar that has been allowed to cure and harden. (This was the original material used to bed window frames). In some circumstance inert filler boards or suitable packing can be used. Keep the joints slightly recessed 4-5mm. Mastic should not be used to make up damaged or defective stone or render. These should be repaired before with natural stone repair and / or lime render products. If the masonry has a high surface absorbency use tape to protect and mask the masonry to prevent undue surface spread.
Timber frames should have loose flaking paint removed and be fully primed and undercoated before applying the finished mastic, ideally wood work is best fully finished, although a final finishing coat may be left until the mastic has properly set.
Application
Burnt sand mastic is a two-part product. For each litre of burnt sand add approximately 250ml of the double boiled linseed oil hardener. Add only a little at a time and mix until the mastic forms a thick putty like consistency, which comes cleanly off the mixing trowel. Let the mix stand on a board for 15 minutes and use any excess oil which runs off plus any remaining oil as a primer, applied with a brush to the frame and adjoining masonry.
Apply the mastic whilst the primer still feels oily or tacky to touch. 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 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
Womersley’s Burnt Sand Mastic is available in Buff, Red, Yellow, Cream and Umber
Coverage = 10L Tub Approx' 30 linear meters with to a 20-25mm fillet
Technical Guides
Colour Swatches
