How to restore/imitate "cement wainscot" or "Keene's cement" tile
My old house's bathroom has the original fake "tile" made of what may be known as plaster of paris. This is commonly found in old homes and it was made very durably with a glossy tile-like surface.
It's been painted over several times so the depth and definition of the 'grout lines' isn't as defined as it should be. I'd like to I guess you'd say redefine those lines somehow (some sort of tool with a half-circle or roundish end?) but also - where the wall had to be torn out for plumbing reasons - I need to recreate it in one area.
I've searched far and wide for any info on this and have also called plaster people and no one seems to have the first clue. I've seen several pictures on oldhouseweb.com and comments from those having discovered it in their homes but no one willing to restore it or at least knowing how.