Limestone mortar staining - Remove mortar stains

Patio flagstones (slabs), concrete flags, stone flags including yorkstone and imported flagstones.
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Millsabelle
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Joined: Fri Aug 03, 2018 8:29 pm
Location: Northumberland

Post: # 116128Post Millsabelle

Hi. I know this will have been covered but can't find the answer. I have laid a black limestone patio and got mortar staining all over. I have asked landscape gardeners and done Google searches and all except this site say to use acid based cleaners. Reading through paving expert it says under no circumstances use acid but does not seem to advise what to use, I can only find sealers and colour enhancers. Really hoping I haven't wasted a load of money.
Cheers.

Tony McC
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Joined: Mon Jul 05, 2004 7:27 pm
Location: Warrington, People's Republic of South Lancashire
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Post: # 116149Post Tony McC

God knows why other sites are suggesting the use of hydrochloric acid! That stuff should bnever be used on limestone, and never, ever, ever used on black limestone. Eejits!

You *could* try phosphoric acid - that does work on some occasions - not always, mind, but sometimes. Otherwise, it's as I say on the main website: try a colour restorer or grit blasting, or opt to have the affected flags replaced.
Site Agent - Pavingexpert

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