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Indian sandstone- rust stains and now circular staining

I had an Indian Sandstone patio installed in September. The contractor left lots of sand cement stains on it. When I complained they said 'no problem, they will come around and clean off the stains'. A week following the 'clean' brown staining starting appearing on the patio quite severely over most slabs. I complained and they said they had never seen this before.. long story short, they eventually said it was iron oxide and that another cleaning agent will get rid of it. They have now been over and 'cleaned' the patio again (I am not sure what with) which has actually got rid of most of the rust stains but I am left with very unsatisfactory looking patio still which has patchy circular staining but not rust .... can anyone please advise where the contractor has gone wrong and what I can do about it? thumb_IMG_4886_1024.jpg

4 Answers from MyBuilder Stonemasons

Best Answer

Lots of sedimentary stone contains pockets of iron ore some a lot more than others. Two pieces of stone from the same quarry and cut from the same block can vary massively as one can contain a lot and another almost none. Identifying the pieces should firstly be done at the cutting stage and again at the laying stage although it can be difficult to tell as the ore is embedded and some times difficult to detect. I have known a saw man to use magnets to check the stone. Now if the paving has a high concentration the ore will begin to oxidise (rust) and absorb into the stone as the paving will be wet a lot of the time. You can keep cleaning away the rust but it will always return but less each time or until the ore has gone but generally this takes a very long time. Allowing the paving to weather will help the darker patches to not appear so severe. It is a natural product and flaws like this are quite common, liken it to knots in wood.


Answered 16th Sep 2016

If you have circular staining on the flags it might of been spot bedded causing moisture to appear where the mortar is in contact with the flag.Flags should always be laid on a solid bed and the underneath coated with a slurry mix preferably nhl lime before bedding


Answered 25th Nov 2019

Should have gone to the supplier and asked the question not the contractor


Answered 5th Jul 2017

I'd also agree with a previous answer to maybe check the slabs have not been spot bedded, try tapping on the slabs with your nuclear or something hard and it should sound solid and you shouldn't hear and hollow spots that sound like there echoing


Answered 26th Sep 2023

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