Stains on concrete sills

[Musky65]

Hi

Anybody got any tips / advice on removing some stains left by external render (now removed but leaving stains) and soil (hand prints) on brand new cream coloured concrete window sills?

[Tony McC]

The soil will come off with hot, soapy water and a scrubbing brush, but as for the render ....removing cement staining from a concrete product? Damned near impossible.

[Musky65]

oh dear, what about a cement cleaner, or is that the point that the stain is cement ?

[lutonlagerlout]

general practise is to tape up these type of sills when rendering,they aint cheap and the plasterer should be aware of that
LLL

[Tony McC]

A "cement cleaner" will eat away the cement, including that used to form the cill. Even worse, as this is a coloured concrete cill, the acid (which is the active ingredient in the cleaner) is likely to darken what was cream to buttery yellow or even edge it towards orange (due to cement dyes being based on iron oxide)