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Landscape Gardening
Strange patches appeared on my new indian sandstone path and garden
I had my old concrete flags lifted and replaced with Indian Sandstone paving. It look great at first, but now, several strange patches of brownish stain have appeared, looking like something was spilled, not cleaned up, and been absorbed by the stone, although nothing has. I have tried washing and scrubbing with a stiff brush and Baby shampoo solution, but it has done nothing to help. There is also the ubiquitous green algae which I hope to remove later with a weak solution of household bleach and maybe gently power washing....some of this has been improved when I was trying to scrub off the stains
Any thoughts or advice please, the stains are a mystery.
Thankyou in advance
Many thanks Sandau Enterprises. Marshalls, said baby shampoo was gentle and that nothing harsh should be used to clean the Indian Sandstone. The retailer also advised against power washing, but my very large back garden and front path are now looking terrible with patches of green, brown and 'clean' where the rain seems to have washed it, and my effort to remove the stains has failed, but cleaned the algae and dirt away. I feels happy to do as you say and power wash it in the spring and then have it 'sealed', but will this stop any further stains coming, what product should I ask the tradesman to seal it with and roughly how much per sqm is reasonable in my area, (Cheshire, but not the posh part!) to ask them to clean and seal the areas? I paid £10.000 for my new landscaping and begin to regret having Indian Sandstone, however, it seems daft to just let it get worse, and to get it sorted seems to make good sense.
Yes, the Landscapers were registered Marshalls installers, but I do not know if all the right things were done, because I left it to the 'experts'.
I had not considered whether this was 'cheap imported sandstone', because I didn't think Marshalls would sell stuff that was no good.
3 Answers from MyBuilder Landscape Gardeners
Best Answer
The stains will be minerals coming through, so salts primarily.
These should go in time as water flushes it out. You can speed this up by washing it frequently. But NEVER when you expect it might be frosty as that will shatter the slabs.
You can use a pressure washer to clean the algae off no problem and this will help to rinse the slabs too.
Never heard of anyone baby shampooing their slabs before. If you use a bleach it is likely to lighten the colour, so be careful on that front too.
Once you have finally got rid of the stains and the algae I strongly advise that you put a sealant on the slabs. This reduces further staining, slows algae growth and reduces the likelihood of frost and ice shattering them.
Sealing them before they are clean will only seal the marks in!
Hi,
I use this stuff to seal the slabs I put down:
http://www.homebase.co.uk/en/homebaseuk/thompsons-clear-one-coat-patio-and-block-paving-seal---5l-265610
I would also suggest either getting a cheap sprayer or brush it on yourself, I would not pay someone else to do something as simple as this. The instructions are pretty obvious, make the slabs clean and dry and brush/spray it on. There are cheaper places to get it from too so by all means shop around. The best price I found was about £18-19.
假设you follow the instructions, when you are happy with the cleaning results, there shouldn't be any more marks after that. I have never had any, but you never know.
Obviously sealing it too soon will seal any stains or marks in, so don't jump the gun.
Pressure washers come in various forms, from barely making a damp patch to cutting steel plate for warship's armour. A basic cleaning one for around the £100 mark will be perfect, something like the Karcher K2.
The situation is being caused by the stones being laid flat and the salts coming up as rainwater flushes them out. To speed this up, simply wash them every now and then, I have even used one of those up and over garden watering bars to water them slowly and bring the salts out quicker. If you do this, remember to flush the salts away or they will just go back in as they dry. Hopefully that's obvious.
You may never get 100% of the marks to go, but you should expect 95%+.
You can wash it as much as you want, just don't do it if there is a frost likely.
I wish I had this job, but you are a tad far away, I'm near Brecon in Wales, I'd have gone through all this as part of my quote.
Answered 8th Mar 2017
The first question, was it installed my a Marshall's registered contractor. If so it should be covered by their guarantee. Second were the slabs laid on a full bed of mortar and the backs of the slabs washed with a PVA/cement wash or equivalent. Third were the slabs up to British standard. A lot of cheap Indian sandstone is porous and can become susceptible to algae. If you want more info feel free to contact me. Regards Graham Patios and Drives
Thanks for your reply.
If the product was a Marshalls product and the installers are Marshall's registered then please contact Marshalls and they will sort it out.
Answered 12th Mar 2017
Pour bleach on the slabs and wash off in 30 mins sorts this problem out .
Answered 4th Jul 2019
