Limestone patio cleaning - Cleaning limestone with citric acid ?

[stevieb]

Hi, i have been looking through the posts and see that using patio cleaners with acid is a definite no no. I was wondering whether i could use a 10% solution of citric acid as i do not believe this is as agressive as the standard patio cleaner acids. (though i do not own a white coat and so may be wrong on this).

[Pablo]

What are you trying to clean off the flags?.

[stevieb]

Hi Pablo, i am trying to clean off mortar marks as the patio was black limestone, was only laid last august and now looks like light grey !!

[Pablo]

Limestone will go grey if you don't seal it soon after laying. Maybe try powerwashing with a turbo lance and a 3000+psi washer. Stay away from your pointing. Tiler's use alkaline cleaners for this kind of thing but I have never had to use them. Power wash it then test a samll area with a QUALITY sealer and see if it covers the problem over.

[stevieb]

thanks for that, any recommendations for the quality sealer ?

[Pablo]

Lithofin stay away from the cheapies like Thompsons they'll break your heart. I get mine from a tile shop.

[RAPressureWashing]

Be careful with Citric Acid, you could turn your Black limestone White, citric is usually used as a brightner or neutraliser not a cleaner.

[stevieb]

OK, many thanks for that. I have been advised to wet the patio and if the marks dissappear then i should be ok to just seal it only.

[Pablo]

Nooooooooooooooooo! Once the sealent weathers the marks will start to show through again pretty quickly. Get them off as best you can then seal it.