A cleaning question. - Spray paint and mortar on sandstone.

[Branston]

Apologies this question is a bit off topic regarding paving, it’s more a cleaning question.

If Roger or other experts on these points are on hand I’d be most grateful.

I’ve recently attempted to clean an Indian sandstone patio. It hasn’t been sealed at any point since it was laid and wasn’t in a good state.

The customers had removed the loose pointing and we’d agreed to repoint it once cleaned.

Prior to this, during repairs to their home, they/workers have dropped a fair bit of mortar onto several stones which have been allowed to set/simply not cleaned up. They’ve also spray painted, outdoors, a small fence. This has sprayed lightly a few slabs in the process (Not much but a noticeable spray effect if you look at it closely)

What would you use to remove mortar from Indian sandstone? It’s very firmly set. I'm well aware acid doesn't fare well on sandstone and I hate using the stuff full stop.

Equally I’m not sure what to use to remove the spray paint.

I’m assuming it’s permanent? Same as sealing with pigment I’d have thought?

Any help would be greatly appreciated.

Regards,

Richard.

[RAPressureWashing]

Richard
Do you have any photos you can put up to see the spray paint & how bad the mortar staining is? Is it more of a mortar haze? or are they snots?

[Branston]

Hi Roger,

Many thanks.

I don't have a photo of the paint but I will get one. I should have taken one but with the dirt and lichen it wasn't even visible post clean.

It appears the folks took it upon themselves to spray, as opposed to hand painting, a small fence, while not bothering with any ground protection. It's very minor and barely noticeable, thought you can see it on close inspection.

It's literally a very small amount, lightly sprayed but it's not moving and the customer wants it off.

As for the mortar, I've attached a photo post clean. It's much better now just some small patches of heavier debris.

Any advice would be appreciated and thank you Roger.

Regards,

Richard.

[Branston]

Hi Roger,

Many thanks.

I don't have a photo of the paint but I will get one. I should have taken one but with the dirt and lichen it wasn't even visible post clean.

It appears the folks took it upon themselves to spray, as opposed to hand painting, a small fence, while not bothering with any ground protection. It's very minor and barely noticeable, thought you can see it on close inspection.

It's literally a very small amount, lightly sprayed but it's not moving and the customer wants it off.

As for the mortar, I've attached a photo post clean. It's much better now just some small patches of heavier debris.

Any advice would be appreciated and thank you Roger.

Regards,

Richard.

[RAPressureWashing]

Richard,

For the mortar hazing Phosphoric acid substitute is fine on sandstone, you can get this from Tiling Logistics (Birmingham) or their web-site, Just read the instructions for dilution rates etc subject to the soiling of the mortar etc.
Re-the fence paint? is it a well known brand? Ronseal or Cuprinol??

[Branston]

Many thanks Roger,

The spray painted slabs are being replaced, so all is good there.

Regarding the mortar stains. It's actually I reckon a bonding agent mix that's fallen down when someone filled in some holes on the side of the house.

Is this the phosphoric acid substitute you meant?

http://www.tilinglogistics.co.uk/aqua-mi....stitute

Many thanks for all your help Roger.

Richard.

[RAPressureWashing]

Yes that's the one, I have used it, on sandstone, you might have to do a clean a couple of times, as just be careful with contact/dwell times couple of minutes tops, then flush-wash off, and if necessary re-apply

[Branston]

Great. Many thanks again Roger.