Difficult to photo, just a uniformly white matt wall. BTW there's original fitted carpet in the bottom - so I'm sure there's never been a dampness issue (also is smells dry).
Don't really know about 'efflorescence'. After googling I think its a salty deposit left when cement dries. If so, then I don't think I have that (did I mention that I didn't need a drill and rawlplugs to put up the rail - just selftapping screws and my electric screwdriver).
I thought I'd help out my girlfriend by converting a large cupboard inside the front door into a coat-cupboard - so I put up a rail. But damp coats keep getting white marks off the walls. I tried washing the walls - lots of white came off - but it didn't help. The walls are white, matt, and I think ...
