[Wolfman]

Got some Indian sandstone to clean.   Should I pressure wash it before I put down the hypo to get rid of dirt. I was going to put the hypo down with a watering can then brush it in.   

Regarding clothes, I was going to wear goggles and a P3 mask and my rain gear.

When rinsing the hypo off after 30 mins of it being on surface will it wash into the grass and damage it?   I will have drenched the grass with water before.

[Kev Martin]

Never PW Sandstone pre wet it with clean water and then clean it with a Mono Rotary Machine with High Alkaline in the tank extract, rinse and extract again.  Then seal it with a premium impregnating sealer

[Mike Halliday]

What condition is the pointing in? As long as it’s in good condition then powerwashing will be fine, Kev method is also an alternative but 99% of professional powerwashing companies are cleaning Indian stone with their normal equipment,   regarding the  pointing, some companies are using a brush-in product that does not have the strength of a wet mortar pointing so can be slightly weak testing in a inconspicuous area might be advisable unless you have the knowledge to recognise the method of pointing that has been used.

The procedure you describe will be fine, you will find after the first initial powerwash it will look amazing and unless there is lichen spots Hypo might not be needed.

Some example.......

[Splash & dash]

Never PW Sandstone pre wet it with clean water and then clean it with a Mono Rotary Machine with High Alkaline in the tank extract, rinse and extract again.  Then seal it with a premium impregnating sealer

Why shouldn’t you pressure wash it ? I have done hundreds of sm of it and never had a problem , apart from some of the mortar between the slabs coming out

[Kev Martin]

Never PW Sandstone pre wet it with clean water and then clean it with a Mono Rotary Machine with High Alkaline in the tank extract, rinse and extract again.  Then seal it with a premium impregnating sealer
[/]
Why shouldn’t you pressure wash it ? I have done hundreds of sm of it and never had a problem , apart from some of the mortar between the slabs coming out

Wow 100’s of M2 and never had a problem?  Oh well I must be wrong then!

[Wolfman]

The pointing looks good.   So just pressure wash it with my b and q pressure washer?   I thought hypo would do the same and not damage the pointing.  Ok I will just pressure wash it.  Maybe don't put too much power on pointing area though.  She did say she didn't want it pressure washed.  Would hypo do the same job or does the surface dirt need jet washing?

[Splash & dash]

Never PW Sandstone pre wet it with clean water and then clean it with a Mono Rotary Machine with High Alkaline in the tank extract, rinse and extract again.  Then seal it with a premium impregnating sealer
[/]
Why shouldn’t you pressure wash it ? I have done hundreds of sm of it and never had a problem , apart from some of the mortar between the slabs coming out

Wow 100’s of M2 and never had a problem?  Oh well I must be wrong then!

No Ime not being sarcastic Ime asking someone who’s an expert in the field of cleaning this type of surface why shouldn’t you pressure wash it ?  As I said I have cleaned hundreds of sm of sandstone and never had a problem have I just been lucky ? Why shouldn’t you pw it ? Why dont you explain the reasons why ? I was hoping to maybe learn something from you but then again I doubt it as you make sarcastic comments but add nothing constructive to explaine why you shouldn’t use a particular method ,

[Kev Martin]

Then maybe you need to look again at your methods.  Stone,  especially the softer varieties of sandstone and Limestone depending on where they are on the rock cycle have varying degrees of hardness on the mohs scale.  Pressure washer guns, nozzles can damage the surface beyond repair if not used correctly.  This is especially prevalent with cheap PW’s in the hands of novices.  The problem is exacerbated when the same novice get their hands on Hypo and start mixing it and then applying it because they want a quick result.  A bit like the novice bricklayer who thinks brick acid is the solution to any problem.  The golden rule of cleaning ANY surface is firstly to identify it, assess the contaminants and then clean it in the most effective way without doing damage to the surface or the surrounding areas.  If you were to burn a glass dish in an oven,  you can either go mad and scrub it off with a Brillo pad or soak it overnight in some warm water with a bit of fairy and wipe it off with a microfibre cloth the next morning.  The result is the same!  Which would you rather do?

[scott johns]

great reply and very well explained soft washing does far less harm to the stone and pointing.

[Splash & dash]

Showing my ignorance if you use a mono rotary machine how do you clean into corners that are square with a wall around it ? How long does it take to do a job compared to pressure washing ? Will these machines clean into a deeply textured surface , or where there may be natural INdentations  in the stone ? Never having used one I have no idear , I assume that they are powered by electric is this mains or can it be run off a gennie ?  What kva would be needed and what’s the cost of a machine ? Can they be used on block paths and drives and again will they remove moss etc between the bricks ? Sorry for all the questions but Ime intrested in increasing my knowledge and if there is a better way of doing something Ime happy to learn and give it a go , any info would be good thanks

[BDCS]

What have you started ? I have the machines to use both methods and have done. You can run a mono from a 3.5KVA gennie but I take my 6.5 as thats what I use for the gutter vac. You can get a mono in a lift to clean a roof terrace and run it through a house. You can make a very nice job of sandstone with high alk or weak hypo mix with a mono. It's also easy to fix pointing with a brush in resin pointing. I also pressure wash sandstone. Someone suggests an alternative method and it's up to you if you accept that method but there is more than one way to skin a cat. If you buy a mono you'll need a stiff brush for outside jobs. You can do the corners with a hand brush or even a nail brush if your a perfectionist like me

[Splash & dash]

What have you started ? I have the machines to use both methods and have done. You can run a mono from a 3.5KVA gennie but I take my 6.5 as thats what I use for the gutter vac. You can get a mono in a lift to clean a roof terrace and run it through a house. You can make a very nice job of sandstone with high alk or weak hypo mix with a mono. It's also easy to fix pointing with a brush in resin pointing. I also pressure wash sandstone. Someone suggests an alternative method and it's up to you if you accept that method but there is more than one way to skin a cat. If you buy a mono you'll need a stiff brush for outside jobs. You can do the corners with a hand brush or even a nail brush if your a perfectionist like me

Thanks for that I do 1000 s of sm per year of block, concrete and a very small amount of sandstone as it’s not very common where I am although more people are starting to have patios made with it : I always try to give my customers the best service I can , and the sandstone I have done so far has come up well I don’t blast it on full pressure I adjust the pressure for the surface Ime cleaning , it just seams some say it’s fine to pressure wash other say you shouldn’t I have never caused any damage to the surface apart from blowing the odd bit of pointing out but you expect that if it’s brocken up any way, Ime always willing to learn new ways of cleaning things and after Kevin’s comment wondered if I was doing it all wrong and likely to cause damage to the surface m Ime not a fool but sometimes you do need to do things differently life is a learning curve : thanks for your advice

[BDCS]

Ain't a right or wrong way just different people opinions ! Do what works for you

[Kev Martin]

There are loads of you on here with plenty of experience such as Carl from BDCS and Mike from Henry Halliday to name but a few who will never do any damage to soft stone.  But trust me I have seen £1,000’s worth of damage done to softer stone and the surrounding areas all through the misuse of a pressure washer or wrong mixes of Hypo.  Whether you are an expert or not it is unlikely any damage will be done with a Mono Rotary and some High alkaline diluted correctly and given a dwell time.  Furthermore, for the inexperienced among you there will be less mess than with a pressure washer.  This is based on my experience  who has done a considerable  amount of work using both methods.  As Carl says there is no right or wrong method .  It is what suits you and the situation.  Sometimes you can’t use a pressure washer.  What you going to say then?  “I can’t do it”. Or are you going to flexible and adapt and overcome?

[Mike Halliday]

I’ll quickly post this video (which looks totally irrelevant) but at the beginning show a pressure washer being used to clean an exspensive 100% wool rug.

Pressure washers are capable of damaging surfaces but in the right hands can clean safely without damage,  it’s about the knowledge of the operator

https://m.youtube.com/watch?v=5kyiccMFfuw

[Wolfman]

I think I have lost the mono cleaning attachment Nilfisk cleaner maybe hold the lance higher so less power.  if hypo 3 to 1 with watering can then rinse off?   How about getting this-

https://www.amazon.co.uk/Nilfisk-Compact-Cleaner-compatible-Pressure/dp/B01G5482YK/ref=sr_1_15?s=diy&ie=UTF8&qid=1522664259&sr=1-15&keywords=nilfisk+pressure+washers

out of interest would anyone let me come out with them for a day?   There's nothing like seeing things actually done.  Out of interest, decking?   Is that also ok with a pressure washer?

[Jonny Swirljet]

Reading this thread has certainly provoked me into applying extra caution when cleaning/jet washing any type of surface now. Members of this web site, who have a vast experience of cleaning and choose to post opinion or guidance for others to heed is done in a benevolent way. If one newcomer benefits from this thread or inserts caution into the over confident then I feel the web site is achieving its objective. Thank-you universe

[Splash & dash]

There are loads of you on here with plenty of experience such as Carl from BDCS and Mike from Henry Halliday to name but a few who will never do any damage to soft stone.  But trust me I have seen £1,000’s worth of damage done to softer stone and the surrounding areas all through the misuse of a pressure washer or wrong mixes of Hypo.  Whether you are an expert or not it is unlikely any damage will be done with a Mono Rotary and some High alkaline diluted correctly and given a dwell time.  Furthermore, for the inexperienced among you there will be less mess than with a pressure washer.  This is based on my experience  who has done a considerable  amount of work using both methods.  As Carl says there is no right or wrong method .  It is what suits you and the situation.  Sometimes you can’t use a pressure washer.  What you going to say then?  “I can’t do it”. Or are you going to flexible and adapt and overcome?

Thanks for your comments I am very experienced with pressurewashing concrete and block drives , but have little experience with sandstone as it’s not common where I am , I do understand it’s a lot softer so care needs to be taken , I have never used a mono rotary as most of my work can be done safely with pw to invest in extra equipment at the moment for this type of work probebly wouldn’t be cost effective as we don’t do much of the softer materials and generally only do paths patios drives decking , garden walls for existing customers , however if things alter I would seriously consider getting one : I would also have to make some room in my garage as it’s already overflowing with work kit 😂😂😂😂😂

[Wolfman]

Ok going to scrub decking with washing up liquid and stiff broom then pressure wash from a distance.  This is conservative way so I won't damage anything.

The sandstone I will use hypo 3 to 1 with watering can then rinse off with hose pipe after 45 mins.   Will just do a few slabs as a tester to see how it all works out before doing the whole patio.   There's more to this game than I thought.  I will drench surrounding plants as well with water before working

[BDCS]

We may have said there is more than one way of doing it but I never saw that method