White lichen

[zzr-matt]

Evening chaps, my block paved drive was recently washed with sodium hypochlorite at a 5 to 7.5% concentration.

This has removed all the algae etc and taken out the black and yellow lichens. However quite a few areas have heavy white lichen infestations.

Is it best to hit this with hypo again or is there a better method like a biocide etc that would get them shifted even if it takes a while?

[Tony McC]

Try with the super-bleach again, and then follow-up with a good quality biocide.

For some reason, even though everyone moans about the 'black spot' lichen, it's the white one that's a bugger to shift!

[zzr-matt]

Thanks Tony. Any recommendations on the biocide front?

[zzr-matt]

Here is before and after shot either side of the drain to show the improvement with a single hypo application... Ill see what the second hit yields, would you recommend a neat application or keep to 7.5% ish?

[Tony McC]

Keep it dilute.

Who did those mitre cuts? Someone who had 'heard' about the technique, but never actually done it.....they're the wrong way around!!!!

[zzr-matt]

If you are worried about the mitres then I won't show you the slips and darts...

I hit an area with another 7.5% hypo solution and left it a long time with no noticable improvement in white lichen. Im tempted to keep hitting it every few weeks as surely they will give up at some point!

[Tony McC]

Did you look at the Biocides page....? https://www.pavingexpert.com/maintain_04

[zzr-matt]

I did mention biocide above but I hadn't seen you page.... looks like there are good results.

Is there a product you would recommend?

[RAPressureWashing]

The cleaning solution on the stains removal page will get rid of the White lichen, (it's the one Tony calls "Roger Super Jollop" or something like that) You have to be starting with Sodium Hypochlorite at 14-15% in neat form, to dilute down the percentages show in the thread. Just follow the instructions and it will do it, you may need a second application & longer dwell time if they lichen is stubborn.

[Tony McC]

I can certainly vouch for Roger's Super Jollop (I even had a caller ask for it by name a couple of months ago!) but if you want to rely on a good biocide for longer term protection against re-colonisation, then the best I've found so far is Wet & Forget.

[zzr-matt]

So what you guys are talking about is 7.5% hypo with a couple of squirts of johnsons baby shampoo to make it cling?

Well I hit the area with another splash of hypo yesterday and achieved these results (no chems, hypo 1, hypo 2). Not too bad.


Its still clinging on in some areas so may do one more hit.

Ive then been looking at sealants and the kind people at resiblock sent me some samples to try. I dug out some spare blocks to see the effect it has and its quite dramatic. I like how they look after its dried. What is the professional verdict? (Untreated left side and treated right)

[Tony McC]

I used Resiblock on my CBP driveway 10 years ago. It's dulled since then, and no sealant protects against algae/lichens for more than 3-4 years, but it's so easy to maintain with just a twice-yearly application of biocide.

It's the only sealant I would consider for CBPs.