Sika® Black Jack®-903 Bitumen Trowel Mastic

Bitumen in white spirit, gas oil.

24 months from date of manufacture in unopened and undamaged containers.

Contains a flammable solvent and all precautions against fire must be taken during storage. Store between +5 and +25 °C.  

ca. 1.45 g/cm³ at +20 °C.

Resistant to: most salt solutions, dilute acids and alkali, and water.
Not resistant to: oils, solvents and some detergent solutions. 
If not sure, check first in an inconspicuous area.

-10 °C to +50 °C.

Will not flow or sag within service temperature limits.

+5 °C to +40 °C. Surfaces must be free from ice and water.

+5 °C to +40 °C. Surfaces must be free from ice and water.

24 hours to develop a surface skin, the mass below remaining plastic for many months.

At 2 mm wet thickness:  Approx. 0.5 m² per L.

All surfaces must be dry, stable and thoroughly cleaned to remove all traces of dirt, dust and grease. Wet surfaces should be brushed free from water and wiped with a dry cloth to remove any moisture which remains. Stick down loose felt etc. with Black Jack® 904 Roof Felt Adhesive. Metal surfaces should be wire-brushed to remove rust. Where long-term protection is required an initial treatment of a rust-inhibitive product such as red lead or zinc phosphate should be used. Loose or blistered paint should be removed, as should tar-based paint systems. New galvanised surfaces should be roughened with a wire brush or treated with a proprietary etch primer. Where there is green growth present, clean surfaces with Sika® Mouldbuster as directed, before proceeding. To assist in cold weather application, store the material in a warm room overnight prior to use.

Sika® Black Jack®-903 Bitumen Trowel Mastic is ready for use and should not be thinned. Apply by steel trowel or putty knife.

CRACKS AND HOLES

Force the compound into the crack, but finish with a 25 mm band at a 3 mm thickness running the length of the crack. For large cracks and holes, apply the compound over the area to be treated and embed a closely woven glass fibre membrane into the compound to overlap the crack or hole by 50 mm. Allow to dry and then apply a second coat, fully covering the reinforcing membrane.

CORRUGATED IRON/FIBRE CEMENT SHEETING

Tighten loose hook bolts and trowel around with mastic. Remove loose screws, re-bed screws and washers in Sika® Black Jack®-903 Bitumen Trowel Mastic and tighten. Top seal in further mastic and trowel to a smooth finish. If the sheet is cracked, clean and prime with Black Jack®-902 Bitumen and Flashing Primer and apply a bandage strip of glass fibre embedded in the mastic. When dry, overcoat with Black Jack®-902 Bitumen and Flashing Primer followed by Black Jack®-901 Bitumen Paint. Use the same technique for sealing side and end laps in corrugated sheeting.

TILES
Point up butt edges of ridge tiles, fillets and slates with Sika® Black Jack®-903 Bitumen Trowel Mastic.

LEAD AND ZINC
Trowel over cracks and pinholes, where necessary, reinforcing with a woven glass membrane, fully embedded and covered.

FELT
Re-adhere loose felt using Black Jack®-904 Roof Felt adhesive. Apply Sika® Black Jack®-903 Bitumen Trowel Mastic and overcoat with Black Jack®-905 All Weather Roof Coating. Note: felt must be completely dry before applying the mastic.

All tools should be cleaned immediately after use with Sika^® Wonder Wipes or white spirit. Any spillage should be wiped off surfaces before the bitumen has set.