What is Black Lichen

scottish cleaning service said:

I was asked to price a Softwashing job on Indian Sandstone which was covered in Black Lichen. So I wondered why no other lichen bar the black spot variety.

The patio black spots that grow on your garden stonework are actually spots of black lichen. The spores from the black lichen start life as tiny dust-like spores growing on the underside of leaves on trees and plants. These spores are carried, by the wind and the rain, onto your stonework in their millions.

Their backdoor is surrounded by mature trees so maybe that's the reason the patio is covered in black lichen and a bit of a nightmare to get rid of it. If I get the job then I'll take some photos before and after. 

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Pjj said:

Plenty of hypo good dwell time and a decent pressure wash will look like new ??

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scottish cleaning service said:

As simple as that but he wants new Easy Joint mortar brushed into all the joints which have sunk. Its a big job and not bothered if I don't get it.

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Pjj said:

That stuff brushed into the joints will never look right it needs doing with a proper wet mix and a trowel 

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scottish cleaning service said:

I do it all the time now and doesn't stain the slabs and looks great.

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Iron Giant said:

Just in case you get the job and the custy wants the paving sealing seal it first then brush in the easy joint stuff after otherwise if you do the joints first then seal the jointing sand stuff will lift out and have to be redone the joint stuff needs to fully cure otherwise it reacts with sealer 

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scottish cleaning service said:

I was at a potential customers house to price for a monthly window clean and I was looking at his newly cleaned sandstone slabs. All the silka or easyjoint mortar was sticking out way above the slabs. The more I looked at it the more it resembled expanding foam, I have never seen it before. He didn't want to discuss it so we moved on to the windows. Maybe the reason was exactly what you said had happened, bizarre. (I still haven't heard from him regarding windows)

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Iron Giant said:

I reckon that's what will have happened,  my mate said it was nightmare to remove and redo and cautioned me to wait weeks before doing an extra coat of sealer just to be 100% certain there was no reaction. 

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