Area of use
CM 840 Fine is a quick drying, multi-purpose, trowelable patching for underlayment. The CM 840 is suited for new construction and renovations. The product is intended for indoor use on substrates of concrete, lightweight concrete, ceramic tiles, stone, gypsum boards, wood and homgenous PVC.
The substrate should be clean and free of dust, cement skin, grease or other impurities that can prevent adhesion. Adhesion and surface resistance of the substrate should be no less than 0.5 MPa. Always prime the substrate with PP 600 and allowed to dry before applying CM 840. In terms of the primer forming a film, the temperature of the substrate must not fall below 10 °C. For best results, the ambient temperature in the work area should be between 10 and 25 °C. At higher or lower temperatures, the time for curing will shorten or extend. With the risk for cracks due to shrinkage or settings in the subfloor, a concrete surface should not be leveled within the first 28 days after casting. As a recommendation the RH in the concrete should have reached RH 90 % as the upper limit for applying the CM 840. In order to avoid drainage pipes from getting clogged, always make sure the drains are properly sealed before pouring.
Mix the dry powder with max 2.25 liter water ( max 18 % ) per 12,5 kg bag. Mix for 3 minutes with a drilling machine and a whisk to obtain a lump free mix. Product may be refreshed by re-mixing but do not ad more water.
Apply the CM 840 to substrate with a steel trowel. After initial set, apx 10–15 min., remove any overlap marks, seams and inconsistencies by scraping with the steel trowel.