Black lichen spots won’t shift

Dazzer · Jul 8, 2018

Hi All

So yesterday I cleaned a sandstone patio that was pretty covered in black lichen spots

First thing I did was to power wash with turbo nozzle to get the worst of it off which came up okay

Then i applied a 15% hypo mix at 4% with surfactant to the wet surface and scrubbed it around and left for about an hour before rinsein off!

When it dried abit it was still pretty much still there which made me think I should I used a stronger mix!

So i made up a small amount of 8% mix to try on a few slabs scrubbed again left for an hour then rinsed off.

Still wouldn’t shift it all so not happy with the end result and the customer too!

Is there anything else I can do or should I have done it a different way?

Any help on this would be much appreciated thanks.

Daz

THL4KEL · Jul 8, 2018

What pressure washer you using?

Dazzer · Jul 8, 2018

Hi

I have 18lpm which should be enough for the job, was going to use the fsc but the mortor joints were old so decided not to!

Daz

Dazzer · Jul 8, 2018

THL4KEL said:
What pressure washer you using?

Do you think I should of spent more time with the pw on the lichen spots before the wash?

Daz

THL4KEL · Jul 8, 2018

I never have this problem mate. The p/w always budgets them. Have you got a pic of them?

Dazzer · Jul 8, 2018

THL4KEL said:
I never have this problem mate. The p/w always budgets them. Have you got a pic of them?

I can get one tomorrow and post so you would normally get rid of them with your pw first and then wash?

Daz

THL4KEL · Jul 8, 2018

Yeah. I've done drives where the bricks have black specs through the brick.. The drive doesn't look great when they have these bricks after the clean..

Pjj · Jul 9, 2018

Strange I do similar to what you have done and never had a problem always 100% gone ?

Dave B · Jul 9, 2018

Dazzer said:
Hi All

So yesterday I cleaned a sandstone patio that was pretty covered in black lichen spots

First thing I did was to power wash with turbo nozzle to get the worst of it off which came up okay

Then i applied a 15% hypo mix at 4% with surfactant to the wet surface and scrubbed it around and left for about an hour before rinsein off!

When it dried abit it was still pretty much still there which made me think I should I used a stronger mix!

So i made up a small amount of 8% mix to try on a few slabs scrubbed again left for an hour then rinsed off.

Still wouldn’t shift it all so not happy with the end result and the customer too!

Is there anything else I can do or should I have done it a different way?

Any help on this would be much appreciated thanks.

Daz

Did you keep the floor wet for the whole hour?

When it is this hot you need to keep spraying it a little now and again to keep the surface wet as dry hypo will do nothing

Incheck · Jul 9, 2018

Yes not going to lie i struggled today it was too hot for softwashing really. Got it shifted but was soaking pretty much constantly

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tench0771 · Jul 19, 2018

sounds like you are suffering boil off in this heat

scottish cleaning service · Jul 19, 2018

I had same problem but all I did was scrub on 15% pure hypo and left for 30mins to see what would happen. The black lichen seemed to vanish and I rinsed off without the PW.

tench0771 · Jul 20, 2018

i found on bad paving go neat y mess about when u can blast it in one hit

scottish cleaning service · Jul 20, 2018

If you PW a patio and still have black lichen then a bucket of neat hypo and a deck scrubber. Then scrub away till your heart's content. Check after 30mins and if its still there then it's probably paint. :1f602:

Pjj · Jul 20, 2018

scottish cleaning service said:
If you PW a patio and still have black lichen then a bucket of neat hypo and a deck scrubber. Then scrub away till your heart's content. Check after 30mins and if its still there then it's probably paint. :1f602:

Lol with your new washer there won’t be any patio left ???????

scottish cleaning service · Jul 27, 2018

Got my first knockback from a Patio cleaning job. Big Indian sandstone patio with some steps up to grass area. Half surrounded by whitewashed walls that had just been painted. She said on the phone there was no lichen on it and then I pointed out all the black lichen on every slab. I quoted 500 for softwashing and 300 to pressure wash it. They preferred the pressure washing even thou they knew it would not remove the black lichen. I knew he was a retired lawyer and she was a know all bar black lichen. I didn't want the job because I would have needed to leave a perfect job, so I went in high saying it would take me two days. First day to do it and second day to catch any bits I had missed or receive a lawyers letter.

scottish cleaning service · Aug 1, 2018

Doing a nice wee softwashing job tomorrow on buff slabs with plenty of black lichen. Going to make the mix half and half and give it a gentle scrub. Will confirm the results tomorrow after I have finished.

THL4KEL · Aug 1, 2018

Take.some before and after pics

scottish cleaning service · Aug 1, 2018

I will try and remember to take a few photos. Another thing I found out is new hypo is better than old stuff that's been lying about for years.

scottish cleaning service · Aug 2, 2018

Just hose down the patio with the garden hose and then hit the patio with half and half and some surfactant. After 45mins I went to check the black lichen which was still there. I then spot treated with neat bleach a few times and scrubbed in. Very difficult to fully remove it. Then after another 30mins I attacked the patio with the turbo nozzle. Most of the black lichen came off but bits at the edge of slabs is near impossible. In the end I am very happy with it, its a neighbor and she is over the moon with it and got another two to do as a result.

Big sul · Aug 2, 2018

scottish cleaning service said:
Just hose down the patio with the garden hose and then hit the patio with half and half and some surfactant. After 45mins I went to check the black lichen which was still there. I then spot treated with neat bleach a few times and scrubbed in. Very difficult to fully remove it. Then after another 30mins I attacked the patio with the turbo nozzle. Most of the black lichen came off but bits at the edge of slabs is near impossible. In the end I am very happy with it, its a neighbor and she is over the moon with it and got another two to do as a result.
View attachment 14483
View attachment 14484

[emoji106][emoji106]looks good.

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