Black lichen on paving

ban-all-sheds

ban-all-sheds

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How best to get rid of this?

Proprietary cleaners, or just sodium hypochlorite?

Or get a man in?

Got 40-50m² to do, and really it's to tart it up on a house I'm selling, so I'm not overly keen on investing a huge amount of effort, (or expense)

Also the grouting between the slabs is loose in places, so I'm wary of being too gung ho with a pressure washer or a stiff brush...
 
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Are you sure it is lichen (usually yellow and grey round here, and forms a hard crust) not dirt or mould?

If you scrub it with a detergent patio cleaner (or Persil) and broom, does it come off?
 
Sodium Hyperchlorite will remove black lichen spots - 10% solution of commercial grade.

Usual precautions for anybody using strong chemicals
 
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Domestic 'bleach' products are usually around 4/5% Sodium hyperchlorite in solution. Commercial Sodium Hyperchlorite solution is usually around 15%.

Usually the branded domestic products are stronger solutions but many OEM products are fairly weak.
 
JohnD said:
Are you sure it is lichen (usually yellow and grey round here, and forms a hard crust) not dirt or mould?
Click to expand...
TBH I'm just going by photos etc on t'interweb - it looks just like what everyone sats is lichen.


If you scrub it with a detergent patio cleaner (or Persil) and broom, does it come off?
Click to expand...
Tried nothing yet.
 
JohnD said:
What we call "bleach" round here.

https://en.wikipedia.org/wiki/Domestos
Click to expand...
What we call "an expensive way to buy it" round here ;)


As NotSoNewboy said:
Domestic 'bleach' products are usually around 4/5% Sodium hyperchlorite in solution. Commercial Sodium Hyperchlorite solution is usually around 15%.
Click to expand...
It works out cheaper to buy the concentrated stuff and dilute it, than to buy off-the-shelf domestic bleach.

e.g. https://www.cleaningproducts.net/liquid-chlorine-sodium-hypochlorite-15.html (just picked at random)
 
D

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