Sika Primer MB is a one-coat solvent-free moisture barrier primer that has excellent adhesion qualities when used over mastic asphalt and old adhesive residue. Fantastic for strengthening dusty substrates and easy to visually control due to its tinted blue formulation. Moisture barrier system up to 4% moisture by volume (75% RH). Drying time - 12 hours at 20C. MB Available in 5kg or 10kg.