tyrolean

I Cleaned some tyrolean render off some engineering bricks and its left a residue on the brick, I have used brick acid, thinners, turps, wire brushes and nothing moves the residue, has anyone had any experiences like this.

I have a 1940's semi which according to the surveyor is coated with a Tyrolean Render. It's looking rather tired and in some places is dis-coloured due to a leaking gutter and there is a little bit of mould. I'm looking for some advice on how to tackle this myself, in particular:- How to clean...