concrete paving slab black marks - is this lichen?

tekud

hello,

after trying powerwashing and also using biocell chlor-kleen extra(& also separately chlor clean), nothing will shift them.

I was using the chlor clean at 1:1.

is this actually lichen? is there some better chemical to use that's available in ireland?

any and all help appreciated

homer911

Yes, thats Lichen, get some concrete cleaner from your nearest farmer's co-up and follow the directions

magicbastarder

doesn't look bad to me; there's nothing wrong with a bit of lichen.

The Continental Op

Can't see why you'd make a massive effort to clean those bits of concrete, dirty they look more like natural stone, clean they'll look like exactly what they are concrete.

10/10 for the photos btw.

tekud

Well, these are the 'before photos' which the driveway looks like roughly 7/8 monhs after power wash and bleach clean.

In my eyes, they look a lot better with marks removed. Brightens up the driveway etc..

1st photo is part of the driveway freshly cleaned. (no replacement sand between pavers)

2nd photo is is part of the driveway when they're not clean (& lichen is present)

3rd photo is clean bleeding in to dirty.

All taken under same lighting condition at same time. All pavers dry to touch etc..

The Continental Op

Sorry OP its down to personal taste, my preference would be for the aged look rather than the clean concrete look.

Don't get me wrong I don't think all concrete should be left dirty looking. The big problem with a lot of modern architecture is the ugly look of dirty concrete but often in a garden I think an aged look is often better.

Perhaps I'd have a different view of your path if it was all one colour instead of being random. The randomness for me works better when the blocks look a bit dirtier and the colours meld together.

btw I'm not trying to offend you its just my personal taste which comes out a little too strongly sometimes because I think as a nation we have a bit of a fetish for cleaning things with a pressure washer.

looksee

I had some old concrete slabs taken up and relaid. There was talk of pressure washing them when he was finished but then he agreed with me that the old looking slabs actually suited the situation (which was my argument from the start) and blended in with an old stone wall along side them.

I like the look of your cleaned paving OP, though that is because it is mixed colours, but I wouldn't be worried about the lichen marks. Its all down to personal preference though - and I have no idea how you get lichen off concrete.

lucalux

https://www.boards.ie/discussion/comment/119155031#Comment_119155031

Sodium Hypochlorite is what I've seen most exterior cleaning companies use. I'd rather the clean look on your driveway too, it does brighten up the place. Available in co-ops and the like, in 25litre black drums.

https://www.youtube.com/watch?v=HQCnMktFUqg

Have a gander at this video, he covers it fairly extensively i think.

Having said that, I think there's a place for the weathered look in a lot of gardens, but some lichen looks better than others imo.

tekud

https://www.boards.ie/discussion/comment/119158213#Comment_119158213

Seen that video alright. Tried the local co-ops but they're not carrying pure sodium hypo at the minute(not sure if temp change or permanent due to some law change). The off the shelf products i used are 10% sodium hypo so still fairly strong and i use them 1:1 and neat but it doesnt penetrate and kill the lichen off completely.

need a different chemical. something like 5% DDAC Solution from mistralni i think but not readily available to buy in ireland.

RainInSummer

https://www.boards.ie/discussion/comment/119158318#Comment_119158318

You can get that alright. Goes by Lancelot Green Clean. There's two mistral sites, one for trade and one for is regular folk.

That said I've ordered from both sites no bother.

https://mistralni.co.uk/

https://mistralie.co.uk/

There's always the nuclear option. 50% DDAC from:

https://www.benzsoftwash.com/collections/all-benz-softwash-chemical-products/products/benz-bio-cleanze-ddac-softwash-biocide

You just dilute it down more than the mistral stuff though. I usually aim for 1.5-2% DDAC.

tekud

Didn't know mistral had retail site. That's great. I'll give that a shot.

magicbastarder

jaysus, it's just a bit of lichen.

https://en.wikipedia.org/wiki/Didecyldimethylammonium_chloride

tekud

https://www.boards.ie/discussion/comment/119160779#Comment_119160779

It is not good looking lichen.

Think of this as eugenics for lichen. only the best looking lichen will survive. this lichen just looks like dirty smudges on an otherwise clean & pure driveway.

from your wiki link:

In mice this disinfectant was found to cause infertility 

Luckily, I'm not a mouse. Are you?

tekud

https://www.boards.ie/discussion/comment/119160779#Comment_119160779

https://www.boards.ie/discussion/comment/119148446#Comment_119148446

I just realised your agenda. You're not a mouse. You're lichen.

Please stop brigading this thread with propaganda.

standardg60

https://www.boards.ie/discussion/comment/119161076#Comment_119161076

It's not an agenda or propaganda, merely concern for dangers to biodiversity, which most gardeners and posters on here would have.

You're planning on introducing highly concentrated bleach to the local environment, bleach belongs in toilets and shouldn't be used outside at all.

matchthis

I moved into a house last year and loads of this all over the place. Was recommended to get Stontex Black spot remover. Think I diluted 1:1 and within an hour, it was all gone. I used a pressure sprayer to apply and power washer to hose away. I’d say I could’ve diluted more. Got it in Tile Merchant in Dublin. They also have option to deliver

tekud

https://www.boards.ie/discussion/comment/119167329#Comment_119167329

It's not an agenda or propaganda

That was a joke.

merely concern for dangers to biodiversity

Seven of those lichen smudges murdered some innocent honeybees. Stop being a bleeding heart liberal. They'll never reform.

wrangler

https://www.boards.ie/discussion/comment/119167385#Comment_119167385

some of those cleaning fluids don't even need to be power washed after, it works away itself.

Power washing isn't good for concrete, particularily the older concretes

Lumen

https://www.boards.ie/discussion/comment/119167595#Comment_119167595

You're probably better off posting in the DIY forum with this kind of question, it's nothing to do with gardening and your blasé attitude to poisoning your environment with chemicals will attract less scorn.

tekud

https://www.boards.ie/discussion/comment/119191260#Comment_119191260

We're all chemicals at the end of the day