Grey fibre plaster/render

[Cadishead67]

I am renovating a 1950s former Manchester City Council house. It has a grey plaster/render on most of the walls that contains thin fibres in it. I have had an asbestos survey and it has been tested for asbestos.

I have included photos. It is lightweight but it is cold to touch (colder than normal gypsum on the same wall). It requires a breaker to get it off.

Does anybody know what it is and why it might be on the walls?

 

[Topspread16]

Probably limelight

 

[malc]

1950s, I am going for Thistle Fibre Browning. this early browning we would put through the mixer 3 to 1 with sand. no idea where the asbestos comes from.
this material was common on government projects, we also floated plasterboard lath sheets with this for some architects.