Substrate preparation
CERESIT CM 42 adheres to all solid, load-bearing, clean and dry substrates free of substances that may impair adhesion. Coatings of insufficient load-bearing strength must be removed. For levelling and raising the level of cementitious floors we recommend using CERESIT CN 39 or CERESIT CN 72. Highly absorbent substrates must be primed with CERESIT CT 17. When installing tiles on existing ceramic or natural stone coverings, we recommend a full-surface coat of CERESIT CT 19.