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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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Getting rid of acid stains on patio
The parents have had a patio laid in Indian sandstone/limestone. Dad
decided to try getting a few mortar stains off with acid-based patio cleaner. After a week or so, the patio has turned orangey-brown where the acid has been. According to paving expert, the acid staining is permanent. :-( Anybody know if you can get rid of acid staining? Oxalic acid-based scouring powder seems to be an option, but paving expert cites oxalic acid as "unproven". Is it worth a go? Cheers, DaveyOz |
#2
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Getting rid of acid stains on patio
"Dave Osborne" wrote in message ... : The parents have had a patio laid in Indian sandstone/limestone. Dad : decided to try getting a few mortar stains off with acid-based patio : cleaner. After a week or so, the patio has turned orangey-brown where : the acid has been. : : According to paving expert, the acid staining is permanent. :-( He or she is probably correct... : : Anybody know if you can get rid of acid staining? snip Sand blasting, removing the stone to below the level of the acid damage - a bit 'kill or curer' though... -- Regards, Jerry. |
#3
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Getting rid of acid stains on patio
Jerry wrote:
"Dave Osborne" wrote in message ... : The parents have had a patio laid in Indian sandstone/limestone. Dad : decided to try getting a few mortar stains off with acid-based patio : cleaner. After a week or so, the patio has turned orangey-brown where : the acid has been. : : According to paving expert, the acid staining is permanent. :-( He or she is probably correct... : : Anybody know if you can get rid of acid staining? snip Sand blasting, removing the stone to below the level of the acid damage - a bit 'kill or curer' though... sandstone is not damaged by acid. |
#4
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Getting rid of acid stains on patio
"The Natural Philosopher" wrote in message ... snip : sandstone is not damaged by acid. So you are saying that the OP is lying?... |
#5
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Getting rid of acid stains on patio
Jerry wrote:
"The Natural Philosopher" wrote in message ... snip : sandstone is not damaged by acid. So you are saying that the OP is lying?... He never said it was damaged. Merely that it tuned red. Painting it with red paint turns it red as well. |
#6
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Getting rid of acid stains on patio
On Sep 10, 3:42*pm, The Natural Philosopher
wrote: sandstone is not damaged by acid. The OP has observed otherwise, and Cormaic's pages at pavingexpert.com also describe the same problem. The various metal salts in the sandstone can react with HCl to produce a different colour. Note: I am pretty sure the OP is describing immediate staining, not a lichen buildup. |
#7
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Getting rid of acid stains on patio
Dave Osborne wrote:
The parents have had a patio laid in Indian sandstone/limestone. Dad decided to try getting a few mortar stains off with acid-based patio cleaner. After a week or so, the patio has turned orangey-brown where the acid has been. According to paving expert, the acid staining is permanent. :-( Anybody know if you can get rid of acid staining? Oxalic acid-based scouring powder seems to be an option, but paving expert cites oxalic acid as "unproven". Is it worth a go? Cheers, DaveyOz Take care with oxalic acid - it is poisonous. It is the chemical whic makes rhubarb leaves dangerous. Malcolm |
#8
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Getting rid of acid stains on patio
On 10/09/2010 16:06, Malcolm wrote:
Dave Osborne wrote: The parents have had a patio laid in Indian sandstone/limestone. Dad decided to try getting a few mortar stains off with acid-based patio cleaner. After a week or so, the patio has turned orangey-brown where the acid has been. According to paving expert, the acid staining is permanent. :-( Anybody know if you can get rid of acid staining? Oxalic acid-based scouring powder seems to be an option, but paving expert cites oxalic acid as "unproven". Is it worth a go? Cheers, DaveyOz Take care with oxalic acid - it is poisonous. It is the chemical whic makes rhubarb leaves dangerous. Malcolm The first thing I'd try is neutralising with washing soda. Not sure why the acid would have produced a brown colour but the salts of said acid may wash off more easily. |
#9
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Getting rid of acid stains on patio
stuart noble wrote:
On 10/09/2010 16:06, Malcolm wrote: Dave Osborne wrote: The parents have had a patio laid in Indian sandstone/limestone. Dad decided to try getting a few mortar stains off with acid-based patio cleaner. After a week or so, the patio has turned orangey-brown where the acid has been. According to paving expert, the acid staining is permanent. :-( Anybody know if you can get rid of acid staining? Oxalic acid-based scouring powder seems to be an option, but paving expert cites oxalic acid as "unproven". Is it worth a go? Cheers, DaveyOz Take care with oxalic acid - it is poisonous. It is the chemical whic makes rhubarb leaves dangerous. Malcolm The first thing I'd try is neutralising with washing soda. Not sure why the acid would have produced a brown colour but the salts of said acid may wash off more easily. Iron in the sandstone? Maybe we are dealing with rust. Edgar |
#10
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Getting rid of acid stains on patio
From: stuart noble
Date: Fri, 10 Sep 2010 Time: 19:42:28 Not sure why the acid would have produced a brown colour It's the action of the acid on ferrous fragments in the stone. See the para beginning "York Stone" in: http://www.pavingexpert.com/maintain_02.htm#acid and the para headed "Concrete Paving" under the pictures. -- Ian |
#11
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Getting rid of acid stains on patio
Ian wrote:
From: stuart noble Date: Fri, 10 Sep 2010 Time: 19:42:28 Not sure why the acid would have produced a brown colour It's the action of the acid on ferrous fragments in the stone. See the para beginning "York Stone" in: http://www.pavingexpert.com/maintain_02.htm#acid and the para headed "Concrete Paving" under the pictures. I cam assure you that all my cheap indian sandstome was washed with brick acid, and no stains resulted. Huge algal blooms did, however. |
#12
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Getting rid of acid stains on patio
In message , Malcolm
writes Dave Osborne wrote: The parents have had a patio laid in Indian sandstone/limestone. Dad decided to try getting a few mortar stains off with acid-based patio cleaner. After a week or so, the patio has turned orangey-brown where the acid has been. According to paving expert, the acid staining is permanent. :-( Anybody know if you can get rid of acid staining? Oxalic acid-based scouring powder seems to be an option, but paving expert cites oxalic acid as "unproven". Is it worth a go? Cheers, DaveyOz Take care with oxalic acid - it is poisonous. It is the chemical whic makes rhubarb leaves dangerous. So ... once applied, don't eat the paving stones -- geoff |
#13
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Getting rid of acid stains on patio
On 10 Sep, 12:04, Dave Osborne wrote:
The parents have had a patio laid in Indian sandstone/limestone. Dad decided to try getting a few mortar stains off with acid-based patio cleaner. After a week or so, the patio has turned orangey-brown where the acid has been. According to paving expert, the acid staining is permanent. :-( Anybody know if you can get rid of acid staining? Oxalic acid-based scouring powder seems to be an option, but paving expert cites oxalic acid as "unproven". Is it worth a go? Cheers, DaveyOz In how much of a hurry are you? I had some Indian sandstone laid (always a mistake: if you want a good job done, do it yourself) by a builder who managed to tread mortar slurry all over the surface, so I cleaned it off with brick acid, and had just the result you describe. Two years on, the excess redness has pretty much weathered away. Cheers Richard |
#14
Posted to uk.d-i-y
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Getting rid of acid stains on patio
geraldthehamster wrote:
On 10 Sep, 12:04, Dave Osborne wrote: The parents have had a patio laid in Indian sandstone/limestone. Dad decided to try getting a few mortar stains off with acid-based patio cleaner. After a week or so, the patio has turned orangey-brown where the acid has been. According to paving expert, the acid staining is permanent. :-( Anybody know if you can get rid of acid staining? Oxalic acid-based scouring powder seems to be an option, but paving expert cites oxalic acid as "unproven". Is it worth a go? Cheers, DaveyOz In how much of a hurry are you? I had some Indian sandstone laid (always a mistake: if you want a good job done, do it yourself) by a builder who managed to tread mortar slurry all over the surface, so I cleaned it off with brick acid, and had just the result you describe. Two years on, the excess redness has pretty much weathered away. Thanks for that Richard; it's nice to know it will weather eventually. I tried the pressure washer this evening and it seems to have dulled it down a little. Parents' pressure washer is a bit crap tho'. Will try with a more powerful PW if the Oxalic acid has no effect. Just to be clear for the pedants, it is in fact limestone, but it is (apparently) sometimes called Indian sandstone. |
#15
Posted to uk.d-i-y
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Getting rid of acid stains on patio
Dave Osborne wrote:
geraldthehamster wrote: On 10 Sep, 12:04, Dave Osborne wrote: The parents have had a patio laid in Indian sandstone/limestone. Dad decided to try getting a few mortar stains off with acid-based patio cleaner. After a week or so, the patio has turned orangey-brown where the acid has been. According to paving expert, the acid staining is permanent. :-( Anybody know if you can get rid of acid staining? Oxalic acid-based scouring powder seems to be an option, but paving expert cites oxalic acid as "unproven". Is it worth a go? Cheers, DaveyOz In how much of a hurry are you? I had some Indian sandstone laid (always a mistake: if you want a good job done, do it yourself) by a builder who managed to tread mortar slurry all over the surface, so I cleaned it off with brick acid, and had just the result you describe. Two years on, the excess redness has pretty much weathered away. Thanks for that Richard; it's nice to know it will weather eventually. I tried the pressure washer this evening and it seems to have dulled it down a little. Parents' pressure washer is a bit crap tho'. Will try with a more powerful PW if the Oxalic acid has no effect. Just to be clear for the pedants, it is in fact limestone, but it is (apparently) sometimes called Indian sandstone. Well if its limestomne why call it sandstone? Indian sandstone is sandstone. AKA fake York stone. IIRC |
#16
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Getting rid of acid stains on patio
geraldthehamster wrote:
On 10 Sep, 12:04, Dave Osborne wrote: The parents have had a patio laid in Indian sandstone/limestone. Dad decided to try getting a few mortar stains off with acid-based patio cleaner. After a week or so, the patio has turned orangey-brown where the acid has been. According to paving expert, the acid staining is permanent. :-( Anybody know if you can get rid of acid staining? Oxalic acid-based scouring powder seems to be an option, but paving expert cites oxalic acid as "unproven". Is it worth a go? Cheers, DaveyOz In how much of a hurry are you? I had some Indian sandstone laid (always a mistake: if you want a good job done, do it yourself) by a builder who managed to tread mortar slurry all over the surface, so I cleaned it off with brick acid, and had just the result you describe. Two years on, the excess redness has pretty much weathered away. Cheers Richard mine washed out with a pressure washer immediataley. Though it took several weeks to develop after serious rain and only developed where the water laid.. |
#17
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Getting rid of acid stains on patio
Dave Osborne wrote:
The parents have had a patio laid in Indian sandstone/limestone. Dad decided to try getting a few mortar stains off with acid-based patio cleaner. After a week or so, the patio has turned orangey-brown where the acid has been. According to paving expert, the acid staining is permanent. :-( Anybody know if you can get rid of acid staining? Oxalic acid-based scouring powder seems to be an option, but paving expert cites oxalic acid as "unproven". Is it worth a go? Cheers, DaveyOz Well, the Oxalic acid worked like magic. 150g/litre in very hot water in a bucket took the stains out in about 10 minutes. I made up 2 litres and by the time I'd used about 1.5 litres, the water had cooled and there was a load of undissolved stuff in the bucket. So I added another pint of boiling water and finished off. 100g/litre would probably have been just as good if a little slower. It leaves little sparkly crystals as it dries, so you need to rinse it off thoroughly whilst lightly scrubbing with a deck brush. Note that they (the parents) have dark grey concrete blocks as a border and these ended up being much lighter afterwards. A further rinse and scrub (of the edging stones) improved the situation no end and I'm sure they will weather quite quickly. Ironically, a further application of brick acid cleaned a sample block up nicely, I just had to be careful not to get any acid on the limestone! |
#18
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Getting rid of acid stains on patio
replying to Dave Osborne, Craig S wrote:
Hi Dave, I've just finished laying 46m2 and cleaned off the cement with what I thought was limestone/sandstone friendly cleaner. This was not the case and I've end up with brown stains, almost a rust colour. I've ordered some oxalic acid and plan to carry out the same as you did on Monday. Can you confirm if your parents slabs are still ok and the stains have not come back please. I'm gutted as so much hard work has gone into this! Regards Craig -- for full context, visit https://www.homeownershub.com/uk-diy...io-655497-.htm |
#19
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Getting rid of acid stains on patio - Update
Dave Osborne wrote:
The parents have had a patio laid in Indian sandstone/limestone. Dad decided to try getting a few mortar stains off with acid-based patio cleaner. After a week or so, the patio has turned orangey-brown where the acid has been. According to paving expert, the acid staining is permanent. :-( Anybody know if you can get rid of acid staining? Oxalic acid-based scouring powder seems to be an option, but paving expert cites oxalic acid as "unproven". Is it worth a go? Cheers, DaveyOz Well, the Oxalic acid worked brilliantly for a day or three, but the brown stains have reappeared over the course of two or three weeks. The stains seem to be more "spread about" and less intense than they were before. We just re-treated with Oxalic again this weekend and again, the brown stains all disappeared within a few minutes. I imagine that the stains will come back, hopefully less intense again. This could be a longish term project to gradually get rid of the stains. |
#20
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Getting rid of acid stains on patio - Update
Well, the Oxalic acid worked brilliantly for a day or three, but the brown stains have reappeared over the course of two or three weeks. The stains seem to be more "spread about" and less intense than they were before. We just re-treated with Oxalic again this weekend and again, the brown stains all disappeared within a few minutes. I imagine that the stains will come back, hopefully less intense again. This could be a longish term project to gradually get rid of the stains. I know this is about 6 years ago now, and the chances of anyone seeing this are slim, but did this eventually work for you? I am in a similar situation. |
#22
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Getting rid of acid stains on patio
Dave, thanks for posting this. I too have a sandstone walkway and steps that I got the acid stains on. I was trying to wash some excess mortar off the steps and walkway using a pretty diluted mix of muriatic acid and water. A few days later nasty orange and yellow streaks and spots showed up where I believe the acid sat too long or didn't get washed off well.
After power washing, bleaching, and other methods I thought I was going to have the remove the yellowed stones. Today I purchased the oxalic acid in a crystal powder form from a local paint store. They are selling it as a deck brightener. I put some hot water in a bucket and dumped some oxalic acid in. I'd guess I put in about two to three cups of powder for about 2 gallons of water. I did not boil it, as it seemed to dissolve fine with the hot tap water I used. I did stir it up. I then poured it over the areas and worked it in with a stiff broom for about 10-15 minutes. I could see most of the stains dissolve about 10 minutes into it and some spots took longer. The water/oxalic acid mix would yellow as it lifted the rust/muriatic acid stains off. I then power washed the entire area really well. The yellow stained stones looked as good as new! I'm guessing like Dave posted that they may return and it will need another washing. I plan to seal the patio once I feel like it is resolved fully in order to prevent anything else like fertilizer from affecting it. Thanks again for this post. |
#23
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Getting rid of acid stains on patio
replying to aaronschoen, KB wrote:
Out of interest did the staining come back. I'm also in a similar situation. I followed your steps above and with in hours the staining is back, as you say less aggressive and more spread out. I'd be interested to know how many washes it took to remove it completely. -- for full context, visit https://www.homeownershub.com/uk-diy...io-655497-.htm |
#24
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Getting rid of acid stains on patio
replying to KB, Cal wrote:
hi, I too am in this mess, first wash of the limestone with Oxalic Acid removed the stains but unfortunately they are back after a few weeks, as mentioned in other responses they are less intense BUT still there. I am now on the second wash with the Oxalic Acid so hopefully this will reduce it further, otherwise I am going to keep the process going and hope that it helps -- for full context, visit https://www.homeownershub.com/uk-diy...io-655497-.htm |
#25
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Getting rid of acid stains on patio
On Tuesday, 22 May 2018 14:44:06 UTC+1, Cal wrote:
replying to KB, Cal wrote: hi, I too am in this mess, first wash of the limestone with Oxalic Acid removed the stains but unfortunately they are back after a few weeks, as mentioned in other responses they are less intense BUT still there. I am now on the second wash with the Oxalic Acid so hopefully this will reduce it further, otherwise I am going to keep the process going and hope that it helps -- for full context, visit https://www.homeownershub.com/uk-diy...io-655497-.htm hi did the stains go ? |
#26
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Getting rid of acid stains on patio
Is this only a year old?
Must be a record from home owners consite. Brian -- ----- -- This newsgroup posting comes to you directly from... The Sofa of Brian Gaff... Blind user, so no pictures please Note this Signature is meaningless.! wrote in message ... On Tuesday, 22 May 2018 14:44:06 UTC+1, Cal wrote: replying to KB, Cal wrote: hi, I too am in this mess, first wash of the limestone with Oxalic Acid removed the stains but unfortunately they are back after a few weeks, as mentioned in other responses they are less intense BUT still there. I am now on the second wash with the Oxalic Acid so hopefully this will reduce it further, otherwise I am going to keep the process going and hope that it helps -- for full context, visit https://www.homeownershub.com/uk-diy...io-655497-.htm hi did the stains go ? |
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