Identify old paint on interior stonework

[Draughtsman]

The stone was repurposed from an earlier building.

Paint is sort of creamy/chalky. Washing it off using water immediately produces a virulent rust coloured stain. Any ideas?

 

[JohnD]

Scrape some flakes off and drop them into small glasses or jars containing

Cold Water

Vinegar

Boiling water

Meths

In order, those will break down whitewash, lime, distemper, and emulsion paint.

The rust stain probably comes from iron content in the stone, but if only on the surface, can be iron particles from filing or knife-grinding.

Depending how hard the stone is, I expect it would come off with a stiff nylon scrubbing brush, or a wire brush.

 

[Draughtsman]

Lime distemper. I think there's iron content in the stone, the rust stains dry out to fine powder and brush off easily with a small wire brush.

There's advice to soften distemper by painting with wallpaper paste and leaving the paint to soak up the moisture, then washing it all off together. The distemper is quite thick in places. Would this stain the stonework?

 

[JohnD]

Lime distemper.

There's advice to soften distemper by painting with wallpaper paste and leaving the paint to soak up the moisture, then washing it all off together.

Where did you see that advice?

I've cleaned off a lot of distemper in my time, and have mixed and applied new.

The glue dissolves in hot water, not in cold. It was often used in bathrooms, kitchens and outbuildings that might be damp or splashy.

Cold water will not wash it off.