Cleaning Indian Paving?

[sblue peter]

Can you help us? We laid an indian stone patio around a concrete pool, subsequently the pool was repainted with bitumastic paint. In doing so the operative managed to flirt or flick paint spots all over the stone work, including some hand and footprints!!. He attempted to clean it off using white spirit and rags but this has only removed some and smeared the rest. Can you offer a better way or suggest a product we could use?

[84-1093879891]

Extremely careful cleaning with white spirit or turps, along with washing down with lots of soapy water.

This will take a lot of time and effort and, personally, I think it would be more cost-effective to replace the flags with the worst staining.

[sblue peter]

Replacing paving seems an extreme solution, do you think brick acid might work or is it too aggressive for the stone?

[84-1093879891]

Oooooh! Never, ever use brick acid with Indian sandstone - it has an awful reaction with the high iron content of these imported flagstones and will ruin the effect. If you think the bitumen-based paint staining is bad, you ain't seen nothing!

Here's some StoneFlair Greyfell riven that was accidentally ruined with acid.....



...you can see an un-stained flag in the bottom right-hand corner.

Going back to what I was saying in another thread, some suppliers are unaware of this problem and have gleefully recommended acid cleaning and then denied any responsibility when the flags have changed colour. However, some of the better suppliers are aware and advise their clients to keep the acid and the flags well away from each other. There is some evidence that the dramatic colour change dissipates over time as weathering neutralises the iron content, but what client wants to wait two years or more for the patio to recover?