What material do you see?

[learning555]

Old brick I removed lime / plaster from. Was very moist. Curious as to what materials that are here, especially the grey stuff which is very annoying to remove.
The white lime (or whatever it is ) comes off easily, the grey stuff I have to use a chisel for, and some black residue appears underneath/ inside it

 

[stuart45]

I'd say the wall's been tanked, then a hard 3/1 sand/cement render and gypsum plaster finish.

 

[learning555]

I'd say the wall's been tanked, then a hard 3/1 sand/cement render and gypsum plaster finish.

Thank you.
The black smearable stuff, chatgpt said it could actually be soat if I had an old furnace that was used to heat the building back in the days- which I do in the basement.
So no risk of asbestos I assume.
The outer layer, you mentioned gypum, how can you tell it's not lime-based plaster?

 

[stuart45]

It's not easy to tell from a photo. Lime will dissolve in brick acid, or vinegar.
Sand/cement will also dissolve in acid, leaving just the sand.

 

[a twig]

Black reside likely some sort of bitumen based paint or coating - our walls had black jack painted underneath the tanking

 

[learning555]

Black reside likely some sort of bitumen based paint or coating - our walls had black jack painted underneath the tanking

I see, yes it might be that. I'm scared that it might contain asbestos, will have to test it

 

[stuart45]

If ever you suspect asbestos, it's worth checking it.
It could be Synthaprufe. In the 70's and 80's, it was commonly used to tank damp walls, especially basements. They used to throw sand on the last coat for a key, then 2 coats of sand/cement render and then gypsum.