Black spots on paths and driveway

Hi all

I've been busy with the power washer today and have cleaned up some of the paths in the front garden. To my amazement, what I thought were all grey slabs were a mixture of cream and grey in a pattern

The only problem is, whilst most of the dirt, muck and moss has been removed, I'm left with loads of black cicular'ish marks, which in my opinion makes the paths look worse than before. The power washer hasn't touched them!

They seem like old moss which has died away and left a form of raised stain.

Any idea on how to remove them?

Thanks, Nick

 

You could use some of that stuff, that gets rid of car oil deposits...any car shop sell it...just a thought:thumb:

 

"Elbow oil", is the old italian expression. Meaning, get to your knees and scrape.

 

Try caustic soda!
Other half cleaned our patio up a treat with it and it is cheap and cheerful....wear gloves though!
Lethal on your skin when its strong
He poured a strong mix on patio - left it for 15 mins and power washed it off easily.

 

Cautic soda or neat bleach. depends how deep the stains are into the flags. Might be easier to move the flags around and put the stains out of sight.

 

Cheeky cheeky :D

Thanks all - I'll give your suggestions a go and then will report back!

 

More pressure ? can you change the end of the lance to get a different jet?