Then it will be convinced that all sheets are securely fixed. After that, thoroughly clean the surface of soot, dirt, moss, etc. D. Then you need to clean the slate of old plaque using sandpaper and treat with antifungal acrylic primer, special for the slate.
And only after this slate must be covered with liquid cement mortar, which in consistency is similar to kefir.After the solution is completely dried, the surface must be primed once again and you can proceed to staining.