Product overview
Bostik Powermastik is a non-drying, oil based mastic, which provides a durable, waterproof seal for gutters, roof bolts, ducting, windows and doors. It forms a protective self-healing skin on the surface keeping the body of the mastic permanently flexible in order to accommodate any structural or thermal movement on the surface. If the skin is cut, the oils beneath will flow and reseal the damage. It remains flexible over a wide range of temperatures, and has excellent adhesion to most materials used in construction. Exhibits excellent adhesion to PVC, polycarbonate, fiberglass, aluminium, steel, galvanized iron, tin plate and other non-ferrous metals, brick, natural stone, glass, painted and varnished surfaces, ceramic tiles, sand cement screeds, concrete, plaster and timber.

Sealing of PVC, galvanized iron and aluminum gutter sections & down pipes.
Sealing overlap joints of roofing sections, air conditioning ducting joints and seams.
Sealing of windows and door frames.
Sealing of roof bolts.
Placing window sills, frames and other fittings where a waterproof seal is needed.
Do not use for floor joints or on bituminous surfaces. Not recommended for high movement joints. Not suitable for continuous immersion in water. Not suitable as an adhesive to bond two surfaces together. Do not use where sealant strength is needed e.g. to hold guttering in position. Application onto porous surface may reduce longevity of the product due to absorption of the oils into the surface.

Can be painted to achieve the desired colour.