This can be done using sandpaper.

Installation of light gypsum stucco molding

It is necessary to get the reverse surface of such products perfectly. This can be done using sandpaper. On the back of the gypsum stucco molding of lightweight, you need to apply high -quality PVA glue in one or two layers, and attach to the wall or ceiling where it was planned to glue it. It is necessary in this position, pressing to hold stucco for 4-5 minutes, until PVA glue becomes thick and hardens.