Rust markings on slabs and oxalic acid

[KAMIKAZEE DIY]

Hello again,

Unfortunately I've managed to cover my slabs with little speckles of rust. Some slabs are marked worse than others and the worst have so much orange tinge theryre likely ruined unless it can be removed.
I managed to do this by cutting metal with my angle grinder next to slabs and metal cuttings/filings have covered the slabs.

Schoolboy error, but the damage is done.

I've read up on main site and oxalic acid/ wood bleach is meant to be effective at removing rust marks but it doesn't say much else.

Has anyone tried something similar? How should acid be applied? Any particular product better than the rest?

Slabs are Indian sandstone.

Any help would me much appreciated.

[Tony McC]

As this is Indian sandstone, there's a risk oxalic acid will make matters worse, not better. It's not certain, but it's a definite risk, so try a discreet corner somewhere first before you go daubong the acid all over the place.

Also, it's important to treat the whole of the affected flgs, not just the specks, otherwise you risk getting spots of cleaned surface within the larger area of untouched stone.

However, before going with oxalic, I'd try a commercial rust remover. Weiss RCI has worked well for me in the past, but again, you need to try a discreet corner first.

[RAPressureWashing]

Couple of things you could try before going down the Oxalic route. Phosphoric acid which you can get from Tiling Logistics.
A company called Tensid do rust removers fluid & poultices.
Also I think it is the paving superstore? that are members on here do a rust remover, which they sent me and have tried and was effective on Indian Sandstone.

[KAMIKAZEE DIY]

Thanks for the recommendations.

Going to try Weiss RCI over Pavetuf rust remover purely because Weiss RCI is less than half the price of pavetuf rust remover, if it doesn't work I'll then try pavetuf.

The cost of chemicals should be a fair bit cheaper than replacing the slabs.

Will let you know how I get on.

Thanks.