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How do i remove a black stain on an external wall which was caused by leaking pipe?

A leaking pipe has caused a black 'shadowy' type stain on an external roughcasted wall. Is this stain mould growth? How do i get rid of it without all the roughcast stones falling off?

2 Answers from MyBuilder Stonemasons

Best Answer

A weak brick acid mix applied with a paint brush may loosen the stain and repeating this procedure could loose the stain all together. (the stain sounds like it is a form of mould growth or liken)


Answered 22nd Apr 2012

Have you tired brick acid


Answered 22nd Apr 2012

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