Identifying My Plaster

[Fjordvik]

Hi,

Wonder if anyone can help me. I'm trying to identify the wall plaster I have. I have been told that they think it could be gypsum then covered with lime but I'm not sure. There's a white layer spanish knife style. under that there is an thin orange layer and the a pinky/brown underneath (see picture). Definitely seems to be gypsum but not sure what's been used over.

Can anyone help?

Many thanks

 

[Wayners]

Pink gypsum.
Original was lime.

Should not use gypsum as it will trap moisture and look like rising damp when it's not

I'm assuming that's an old property with lime plaster walls

 

[Fjordvik]

Thanks Wayners. Would that be they have put lime over gysum of gypsum over lime? the orange part looks to be in the middle and the back part is browny colour. Is an old property yes and the wall is solid wall and other side is covering via alleyway

Cheers

 

[JohnD]

How old is the house

Where is it

 

[Fjordvik]

Approx 100 year old property in Derbyshire area.

 

[JohnD]

The pink and the brown are gypsum. There may well be lime underneath, but you have not shown or described it.

The white swirly stuff is some kind of modern decorative coating. May have been used to conceal cracks or other defects.

There used to be gypsum mines in Derbyshire, you need to ask an experienced local builder or a architectural historian if it was used in your town.

If you cut into the wall we can probably tell by looking at it. Where I live lime plaster is a dirty white or cream.