Cleaning paving slabs

Nigzcurran

Hi I’m wondering is it possible to get these back clean and new looking, the grey ones are ok but the pink are looking terrible, it looks like some kind of mould maybe? I’ve power washed them already. they are around 10 years old, thanks

Alun

It's called black spot, caused by lichens which are a symbiotic combination of algae and fungi. The algal part is mainly on the surface and can be easily got rid off by power washing, but the fungal part has "roots" called hyphae which go deep into the stone and are much more difficult to get rid of.

Here's more than you'll ever need to know about how to try to get rid of them ...

https://www.pavingexpert.com/maintain_03

Nigzcurran

Thanks yep plenty of info and that’s exactly what’s on my slabs, they are pretty old and I’m not sure if they are worth spending much money or hard work on, I might try it on one or two slabs to see how it goes

rob316

Chloras. You can get it in your local co op store, excellent stuff.

JMR

Recent thread related to this

https://touch.boards.ie/thread/2058069806/1

Sodium hypochlorite worked somewhat for me

Nigzcurran

Cheers it’s definitely worth a shot, that before and after pic in the linked thread are amazing