My sincere apologies if this has been asked endlessly.
I've been cleaning patio's and re pointing for about 2 years. When I come across Lichen I tend to follow the paving experts advice and apply diluted bleach, the pressure washer removes it almost all of the time but I've come across a rather resilient lichen, possibly black spot that I wanted expert advice on.
It's only around the edges of an Indian Sandstone patio, by the mortar. It almost looks like an oil satin and for the love of whoever, even my very powerful pressure washer doesn't make much of a mark on it.
I've used bleach, algex and HG green slime remover and several black spot removers but I can't shift it. It's the only stain I've not been able to remove and that includes many with decade old Lichen and this particular attack is only about 3 years old according to the customer.
I've attached a picture and I hope one of you can advise me.
Again apologies if this has been asked many times before, I'm new here and if there's a thread on this please point me there, I did look but again apologies I couldn't fine one on the topic.
lutonlagerlout wrote:what type of bleach are you using? have you tried sodium hypochlorite AKA swimming pool bleach?
LLL
I haven't in all honesty, I'm a bit worried I may damage the stone as it is, I know a place close to me to buy it too. I was also wondering if it was Lichen or something else. It's extremely resilient.
I'll buy some sodium hypochlorite and test on a small patch.
Do you think this is actually Lichen though, not seen something so keen on just the edges of the paving. I wondered if it was something to do with the polymeric sand they've filled up the previously crap pointing. It started appearing after that they said.
You need 13-14% Sodium Hypochlorite, for Lichen this tough, make up a 2:1 mix (2 parts water 1 part hypo) pre-wet the surface first, apply the solution and allow to dwell for 20-30 mins, don't let it dry on the surface, keep topping up if it looks like drying, you might need to do this a couple of times as you can get tough ones at times. If you look on the main site, go to the stain removals page, and scroll down to the berries section, read up on that, but just change the mix ratio to 2:1, if you are still having problems you can go 1:1 but you might need to do the whole area Lichen or not to balance out the cleaning of the stones.
Sorry for my late response and many thanks for the very helpful replies.
I actually have just seen another job that is far worse, can I assume you will need several attacks and is there a point where it's simply not going to bring it back to it's original state? It seems to really attack Indian Sandstone.
May I also ask, is there a particular brand of bleach or sodium hypochlorite any of you have had success with?
Many thanks Roger, I at know at least what percentage Sodium Hypochlorite to use and I'll have a good look at the stain removal/berries page.
Thanks, you've been a great help.
Ps. Just been to the berries section on the stain page. I shall buy some tomorrow, you clearly know your stuff
There's no real "brand" as such, more down to the supplier you use, as long as you get either 13-14% or you make get 14-15% you won't get any stronger then that (as the chemical make-up changes after that) you'll be fine. FYI Sodium Hypochlorite goes into bleach so is not "Bleach" as such, take to long to type the technical stuff though.
Yes you do have to have a second or even a third approach on the really difficult stuff, it does all get down to the dwell time.
Wow, that is a serious lichen issue with incredible results. I'm very impressed.
This new job isn't as bad as that and will require re-pointing after. Pictures below, in the second one are the black marks fossils? The chap said they were but I'd not come across anything quite like it before.
Also did you use the solution to do that mentioned on the stain/berry page? I'm going to buy your whole supply at this rate!
Apologies for so many questions and many thanks again Roger.
lutonlagerlout wrote:errr. they are not fossils, they are iron deposits in the stone cunningly called fossils by stone importers
LLL
That's interesting, not surprising either.
Forgive my asking yet more questions but if you can help I'd be very grateful.
1. Do we need a license of any kind to use this? If so can you point me in the right direction, I have looked but I assume not as it's easy enough to buy.
2. Seeing as it destroys plants and vegetation, are there any tips on where to hose this off too? I've a large area to do and don't want to destroy their grass etc. I just wondered what the best practise was or what you did.
3. This particular customer has dogs, I'm a bit concerned with a. washing it off and b. the dam dogs getting ill.
2, Give the lawn and flowers etc a good water before you start washing, try not to wash towards the lawn or flowerbeds if you can help it. Any tender or low lying plants, we would cover so they don't get covered in crap anyway.
3, Just make sure to flush any traces of the solution away, Rinse, Rinse, and Rinse again if you are not sure.
Do you have a wet-vac? as these can help in situations like this.
Do you have a website or anything?
I'll invest in something to cover plants, lawn etc. I do have a sky vac which can suck any water up so perhaps that's something.
Basically though if it does go on anything, rinse the heck out of it? I'm fine with that.
My website, if I'm allowed to put it here and please delete if I'm not is holliesservices.co.uk, well out of your area though and from what I've seen of you, I'm no threat to you in any way. We're a very young company.
Thanks again for your help, I've added the site to my signature, wasn't sure if if it was something new people should do.
