"rusty" staining on indian sandstone - Advive wanted, please

[clueless]

Hi folks.

Really sorry if this is answered elsewhere, but I couldn't see it anywhere.

I'm in the process of laying a grey Indian sandstone patio. The stone seems to be of good quality, but close to half of them have very heavy staining. It's a tea-coloured marking that looks almost like rust or oxidisation of some sort. Often it's not just in blotches or small patches, but covering up to half of the entire slab.

Can anyone tell me what this is and whether it is likely to fade or get worse? Or should I ask the supplier to change them?

Thanks a lot,

Clueless.

[Rich H]

It's likely to be indelible if it's ferrous in nature. It's caused by the reaction of ferrous material in the stone itself which oxidises in the presence of acidic materials. This can range from brick acid, used to mistakenly 'clean' sandstone through to plain old acid rain.

You need to reject them

Gaffer has more information here: http://www.pavingexpert.com/maintain_02.htm

[clueless]

Thanks, Rich. Much appreciated.

I suppose there's never a good time to admit I've been browsing the rest of this site and realised that up to now I've been laying the sodding things upside down. The stains, of course, are almost exclusively on the side of the slabs that would have been hidden if they had been laid by someone with a brain.

Serves me right for listening to the father-in-law.

[Rich H]

Bad luck. If it makes you feel any better, many so-called professionals make the same mistake. I once almost talked myself out of a job I'd started because the customer was arguing about which way up to lay them.