La limpieza del techo

Cleaning the ceiling in the studio today. It's the vaulted sandstone cellar of the 120-year old building in which I have the shop; this used to be a massage parlour called "Annis", reiki and other therapies offered. Now all that's on offer is reiki and photos. The ceiling keeps shedding little white deposits as the stone dries out (3 dehumidifiers keep damp at bay), and if I don't want to have to clone out bits of dandruff ceiling deposits from studio portraits, regular cleaning is required. I did come out covered in the stuff, and my eyes are still streaming and gritty.