# Clean Patio



## J306TD (May 19, 2008)

What can I use on the patio to try and clean it up?

I've jet washed it with the spinning ball nozzle and angled nozzle but its not really done much









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## Vossman (Aug 5, 2010)

I have this problem too, it's the black mould that remains, I have tried that Spear and Jackson stuff, spray and leave it's called but it didn't do anything after three months of leaving it. 
I tried copious amounts of white vinegar too, poured it on and let it soak then a hard scrubbing, washed off again with white vinegar then powerwashed, maybe 10% better but still can't get the stuff off. 
Bleach I tried but honestly that didn't really do anything either, I think the stain is now in the stone for me.
Oh and I did try a steam cleaner from my sons garage .... you guessed it!


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## Cookies (Dec 10, 2008)

I you know any farmers, try and get your hands on some hypochlorite. It's used for sterilising milking machines, and is serious stuff. It's incredible, but be very, very careful using it.

Cooks

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## J306TD (May 19, 2008)

Cookies said:


> I you know any farmers, try and get your hands on some hypochlorite. It's used for sterilising milking machines, and is serious stuff. It's incredible, but be very, very careful using it.
> 
> Cooks
> 
> Sent from my SM-G950F using Tapatalk


Thanks Cookies.

I guess its a super strength cleaner that will dissolve it?

We've got a dog so thats my concern

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## Taxboy (Aug 23, 2006)

Hypochlorite is basically high concentration bleach. You may never get all the black marks out as I believe it's lichen. but should improve it 
Have a look here 



 and around YouTube

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## MrPassat (Mar 30, 2018)

Milton is sodium hypochlorite, a strong bleach (alkaline).


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## J306TD (May 19, 2008)

MrPassat said:


> Milton is sodium hypochlorite, a strong bleach (alkaline).


We've got that already. We use it once a week on the worktops and tiled floor

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## MDC250 (Jan 4, 2014)

Never tried it myself, but seen a few times now people using Pink Stuff and agitating with a stiff brush. No idea if it works but possibly worth checking.


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## Andyblue (Jun 20, 2017)

Karcher stone cleaner is okay - pop it onto / into your pressure washer and run it through. 

I’ve found the patio cleaner tool works very well and you don’t get wet through. 

Have you got any Surfex HD or Autofoam ? Might be worth a spray (garden sprayer) at a strong dilution and then go over with pressure washer ? I spilt some autofoam last year and had a clean bit of flag


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## pxr5 (Feb 13, 2012)

I've said it before many times but you need BAC-50.

https://job-prices.co.uk/best-moss-killer/


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## J306TD (May 19, 2008)

MDC250 said:


> Never tried it myself, but seen a few times now people using Pink Stuff and agitating with a stiff brush. No idea if it works but possibly worth checking.


The other half did suggest that

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## J306TD (May 19, 2008)

Andyblue said:


> Karcher stone cleaner is okay - pop it onto / into your pressure washer and run it through.
> 
> I've found the patio cleaner tool works very well and you don't get wet through.
> 
> Have you got any Surfex HD or Autofoam ? Might be worth a spray (garden sprayer) at a strong dilution and then go over with pressure washer ? I spilt some autofoam last year and had a clean bit of flag


Got some Auto Foam the other week. Will give it a go 1st

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## Andyblue (Jun 20, 2017)

Hope it works .... :thumb:


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## Rundie (Oct 2, 2007)

Give bleach a try but nothing acidic as it's sandstone and it'll turn orange due to the iron content in the slabs. ****e stuff really, once lichen gets hold it's game over. I've got a Karcher HD with the dirt blaster nozzle and it struggled to clean them up ... I moved house anyway but wouldn't have sandstone again.


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## JB052 (Mar 22, 2008)

Both Grime remover and Swawrfega (both available from Screwfix) are quite good for general patio cleaning. As others have said the 'black spots' are very difficult to remove.


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## GeeWhizRS (Nov 1, 2019)

I hadn't come across Sodium Hypochlorite until this thread a few days ago. My pressure washer won't shift the black spots on our patio so I thought I'd pick some up and try it. It arrived this afternoon. This was the one I picked up https://amzn.to/3d2zaTh

Initially I mixed it up at 1 part Sodium Hypochlorite to 3 parts water and sprayed it on. It cleans algae off block paving for fun at that strength but I was still seeing black spots on the patio. For reference, I did this in a t-shirt and there was a bit of a breeze - after a while I could feel my arms starting to burn, so do this on a calm day and wear goggles & gloves!

I next tried it neat and that has shifted the vast majority of the black spots. (See below.) There is the odd flag that still has black marks so I'm thinking this is a likely feature of the stone. I can confirm this also shifts green/grey lichen that I had on my coping stones.
I'll definitely be using this again and I think would be very useful in freshening up block paving without blasting the jointing sand everywhere with the pressure washer.

Before


After


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## J306TD (May 19, 2008)

Wow thats an amazing difference 

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## kingswood (Jun 23, 2016)

I don't believe a decent power lance on a karcher won't shift it?

mine comes up mint, but the more you do it the quicker it gets stained again? assume ur taking the top layer off and what's below gets stained quicker


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## GeeWhizRS (Nov 1, 2019)

J306TD said:


> Wow thats an amazing difference


Yes, I'm pleased with how it shifted the majority of it; I'd given up trying. Be careful with it though. Glasses/goggles before you take the lid off and throughout its use.


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## GeeWhizRS (Nov 1, 2019)

kingswood said:


> I don't believe a decent power lance on a karcher won't shift it?
> mine comes up mint, but the more you do it the quicker it gets stained again? assume ur taking the top layer off and what's below gets stained quicker


Believe it. My Kranzle K1152 set on a fine jet won't get near it. I would imagine this will vary depending on the porosity of the flag.


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## Andyblue (Jun 20, 2017)

Looks like it’s powerful stuff and works well, one to remember :thumb:


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## grunty-motor (Aug 11, 2016)

This is a task on my list - cheers.

I also need to sort out jointing, if anyone has any tips. I have tried sand, which as expected just comes back out again. I brushed in cement, then wetted it, but the dust goes everywhere and leaves a stain. I have tried mortar mix but waht a slow painful experience that is. Seems sand is easiest and just need to keep doing it?


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## Andyblue (Jun 20, 2017)

grunty-motor said:


> This is a task on my list - cheers.
> 
> I also need to sort out jointing, if anyone has any tips. I have tried sand, which as expected just comes back out again. I brushed in cement, then wetted it, but the dust goes everywhere and leaves a stain. I have tried mortar mix but waht a slow painful experience that is. Seems sand is easiest and just need to keep doing it?


You could try a dry sand / cement mix, brushing that in and then allow the moisture / slightly dampen it to cure it. Depending on size of joints, you could also possibly run over it with a dowel or pointing trowel to compact it ...


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## Taxboy (Aug 23, 2006)

grunty-motor said:


> This is a task on my list - cheers.
> 
> I also need to sort out jointing, if anyone has any tips. I have tried sand, which as expected just comes back out again. I brushed in cement, then wetted it, but the dust goes everywhere and leaves a stain. I have tried mortar mix but waht a slow painful experience that is. Seems sand is easiest and just need to keep doing it?







Does this help. You can also get pre mixed stuff to make it easier

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## GeeWhizRS (Nov 1, 2019)

grunty-motor said:


> I also need to sort out jointing, if anyone has any tips. I have tried sand, which as expected just comes back out again. I brushed in cement, then wetted it, but the dust goes everywhere and leaves a stain. I have tried mortar mix but waht a slow painful experience that is. Seems sand is easiest and just need to keep doing it?


Remove the old mortar and tidy out the joints. Spray water into the joints (don't flood it) to dampen the surfaces so that your mortar won't have the moisture sucked out of it (or it will crumble). Mix your mortar* (as dry as you can get away with). Press that into the joint then 'strike up' when the mortar has firmed up.
Don't point in strong sun unless you have cover and/or can mist the surface frequently. (Also, don't do in very cold temperatures.)

*The mix will depend on your stone or flag. You would want a mortar mix somewhere between 3-5 building sand and 1 part cement (with a dash of plasticiser). If you are using some natural stone or something soft then use more sand in your mortar mix; if a concrete flag you can use a stronger mix as the flag can take it.


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## GeeWhizRS (Nov 1, 2019)

Just as an aside to this sodium chloride thing... I did my parents paved rear yard with it this afternoon. They lost both their dogs due to old age around Autumn but in the areas where they used to urinate, the sodium chloride has had a bit of a reaction and left paler areas on the grey stone paving. I can only imagine there is some chemistry going on with the sodium chloride reacting to the minerals in the dog pee that has built up in the stone. It doesn't look too bad but it's pretty clear it's a reaction to urine. Just thought I'd mention this in case anyone was considering using it and noticed a similar thing. If there are any chemists out there I would be interested in knowing what this is about.


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## GeeWhizRS (Nov 1, 2019)

I used Sodium Hypochlorite on my drive yesterday and created a time-lapse from the CCTV camera. I thought you might find it interesting. 



This is 1 part SH to 3 parts water. Left to dwell for about 15 mins then rinsed off.
:thumb:


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## Carlos Fandango (Dec 24, 2016)

I find sodium hydroxide (caustic soda) is effective for cleaning patios and block paving. Make certain to wear mask, goggles and gloves though.


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## GeeWhizRS (Nov 1, 2019)

Carlos Fandango said:


> I find sodium hydroxide (caustic soda) is effective for cleaning patios and block paving. Make certain to wear mask, goggles and gloves though.


What sort of concentration are you using and how long do you leave it to dwell? Have you worked out the cost?


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