Removing patio black spots

TheCyclingProgrammer

Decided to give the garden and patio a good sort out this weekend - unfortunately our plans to redo our garden from scratch are on hold until next year so I thought I could at least tidy up and clean the patio (which isn't in the best state anyway).

My relatively entry level pressure washer has done an ok job and got rid of the worst muck but I just can't seem to shift these black spots - it's quite bad in places. Is this Lichen? What's the best thing I can use to remove it? We only bought the house last year and it's probably not been cleaned in years.

EssexExile

In my experience that's about as good as it's going to get. We had our patio (which looks amazingly like yours) professionally cleaned several years ago & it didn't get much better. Since then I've done it every couple of years with a big swirly thing on the Karcher & it looks like yours does. It looks better when it dries out.

TheCyclingProgrammer

Well it seems I may have some success with diluted bleach. I might try it one one flag and see how it goes.

I also need to re-point it all too as there's barely any mortar left. Might just use one of those dry brush in ones that you wet afterwards. Only needs to last a year or so.

EssexExile

Looking at the pictures I'd say yours was never pointed, just like mine! I tried all sorts of chemicals but nothing made a significant difference.

Mine is being replaced soon but it looked like that for 16 years, I don't like to rush into things.

TheCyclingProgrammer

You might be right but there is the odd patch of mortar here and there and the pressure washer has probably blasted most of the loose stuff out along with the weeds.

We're also ripping all ours up next year along with the rest of the garden.

brooklyn07

just came across this and have literally just dealt with the same problem.

I tried bleach and lots of other patio cleaners and nothing touched it so i googled it and found "patio black spot remover" - won't put the link in but just google it.

It's expensive stuff by the way but my god does it work!

I've attached some photos for comparison, i had serious reservations given how expensive it was but tried it out last night and i'm absolutely delighted with it!

You will need a pressure washer to get it off with, i dont believe a normal hose will do as good but it just effortlessly comes right off.

I am in no way associated with this company by the way but very rarely do i find a product that actually does what it claims to do but was extremely pleased and surprised in this case!
I didn't take a before pic of the whole patio but the steps are what the entire patio looked like before.

TheCyclingProgrammer

Thanks for the post. I have come across the stuff you refer to but its prohibitively expensive and certainly not worth the expense if we're going to get rid of the patio next year unfortunately. Assuming it does the job in one coat, it costs approx. £3.50/sqm, double that if two coats are needed. I need to cover around 30sqm so I'm looking at two bottles at £70 each. £140 for one coat, £280 for two coats - not worth it unfortunately. Results do look good though.

I'm also not even sure what material my slabs are made from - the look sandstone like but I'm not sure they actually are. They could just be concrete. Can anyone identify from my photos?

brooklyn07

ah fair enough then if you're going to be removing it :-)

Mine is only 3 years old but i bought my house 2 years ago and spent the entire time doing up the inside and completely neglected the outside so was worth it for me plus my patio isn't particularly large as you can see, only used 1 litre and didnt have to go over it twice as i first thought i would have.

thescouselander

What you have there is a bad case of lichen. I've been trying to remove this stuff for years with no luck - it seems impervious to chemical attack, scrubbing and even burning.

I might try the black spot remover though.