Wall

Treehugger
Btw, you can imo safely sand painted surfaces smooth, assuming the most bottom layer(s) are smooth. That means that, if adding primer paint first, then that first layer of paint has to be sanded smooth, in order to be able to sand other layers on top, otherwise, small tips of a bottom layered paint will show through when sanding an upper layer paint. At the end, adding a gloss coat and varnish hides any small discoloration and scratches you get from the sanding. It is important to undertand that sanding details and edges is not possible, because you easily sand away the paint that way, only large flat surfaces are good to sand this way.

Maurice van der Vleuten
good question Martin 🙂