The substrate to which the mortar is applied should be solid, clean and dry, free of poorly bonded parts and greasy stains. The closure of holes, joints, electrical openings should be completed before applying the mortar. In case of applying the mortar to concrete or other smooth surfaces, BK-BetonKontakt should be applied to the substrate in order to improve the adhesion of the mortar. In case of highly absorbent, porous substrates (e.g. siporex blocks), a BK-Nivelator should be applied to the substrate to prevent uneven drying and cracking of the mortar. In case of significant surface unevenness, BK-Mal 120 should be applied first. The preparation of the mortar is done by intensive mixing of the powder with about 22-24% of water. Apply mortar by machine in caterpillar pattern with a minimum thickness of 10 mm and a maximum of 25 mm. After that, spread the mortar with an H-shape plastering derby, trim, felt and level. For larger mortar thicknesses it is necessary to apply the mortar continuously according to the fresh-to-fresh principle, up to the required thickness (max. 40 mm. The mortar must cure evenly. Direct heating of mortar is not recommended. See product datasheet for more detailed instructions.