Sand the surface with Emery Paper 180. Wipe clean with soft cloth. Apply a coat of Indigo Water Thinnable Cement Primer. Allow 6-8 hours for drying. Smoothen the surface by filling cracks with thin coats of Indigo Acrylic Wall Putty and allow 4-6 hours to dry. Sand with Emery Paper 180 and wipe clean. Apply another coat of primer. Sand the surface with Emery Paper