A few years ago, I bought a house from 1897 in Germany. This house has come with quite a few surprises, including today. To my knowledge, it was renovated sometime in the 90s by the previous owner, but before that, I don't know.
Can anyone help me understand what I see on this wall?
On the surface, there is some kind of painted filler and just under it a layer of cement plaster (hard), followed by the dark gray innermost layer that crumbles as soon as you touch it. Any ideas? I have found similar things in other places in/around the house.
Otherwise, this was a fairly traditional house of brick with lime mortar and solid beams but now mostly looks like Frankenstein's Monster.
Thanks in advance!