Rust staining of kandla grey sandstone - Looking for cause and remedy of problem

[nordev]

Hi,
After having researched extensively on this forum, went for the reliable Kandla Grey sandstone paving for my patio which was completed beginning of September 2019 by a professional paver. The jointing compound left oil stains as it was not watered adequately during the process. When I complained they tried to clean with some detergent type stuff (I believe they have not used acid). This did not do anything whatsoever to the stains but after speaking with the company (Azpects Easy Joint) decided to leave well alone, as they said the stains would disappear. But now within a month almost half of the sandstones have become covered with the most horrible patchy brown stain, almost like someone has spilt tea. When I contacted London stone and sent them the pictures ( I cannot insert pictures in this post because it is asking for URL!) they said this was the worst case of iron oxide staining they had seen in sometime and could have been exacerbated by use of chlorine based agents during cleaning. My question is should I accept this and if not what do I say to the contractor who did the job, what can be done to remove these stains? Any advice would be appreciated. I am sorry I cannot post any pictures as I am not on any social media, but am happy to email them if anyone wants to have a look. Many thanks

[Exa]

I have a similar issue here mate: http://ext.pavingexpert.com/cgi-bin....t=15027

[nordev]

Thank you Exa.
It seems like its the same problem, but mine is much more widespread overall and patchy on an individual stone. My first question was whether it was compounded by the contracters using some cleaning stuff to clean the oil stains!
The supplier London Stone are obviously trying to wash their hands off saying it is not a quality control issue and there is no way of saying whether an individual flag is affected or not.

[Tony McC]

If you send the images to me (use "newchurch three two" but as a single phrase [no gaps] with digits rather than spelling out the numbers, then AT gmail dot com), I'll post them to this thread for you.

Without the photies, we're working blind but, generally speaking, you will get nowhere with London Stone as the problems arose after installation, and is a known issue when these polymeric mortars are not correctly applied. And that will be Azpect's fully-justifiable defence: it was the installation that failed, not the product.

So, the next thing is to determine whether the stain is arising from the stone itself (usually rust or iron minerals), whether it's the doping oil used with the polymeric jointing, whether it's a stain from the actual resin binder, or whether it's a combination of these factors.

The doping oil stains do, eventually, weather out, but the tome required depends on just what oil has been used. There were some changes over the last 12-18 months with manufacturers shifting to cheaper, often vegetable-based, oils and these seem to be more prone to hanging around long beyond their initial welcome.

Rust or iron minerals can sometimes be shfited by off-the-shelf rust removers - see umpteen similar threads in this forum.

Resin stains can be more problematic, but there are products out there (such as Resin-Ex) that can sometimes help.

Send me the photies and we'll take a look.....

[nordev]

Thank you so much Tony. I will send you the photos now.

[lutonlagerlout]

I have laid a lot of metres of Londonstone's Kandla grey and IMHO it is the most bullet proof of indian sandstones,not because they sell it ,just Kandla Grey/castle Grey/or light grey is a particularly hard sand stone and not as susceptible to staining as some of the more colourful stone
the problem as I see it a lot of the time is expectation
a patio path or terrace is outdoors
it rains,birds,cats dogs etc do what they do,kids get mud on it
barbecues etc
be interested in the pictures
cheers LLL

[Tony McC]

Did you send the photies? Nothing has arrived....

[nordev]

Hi Tony,
I did on the 8th, to PRIVATE EMAIL ADDRESS DELETED
It has definitely gone, as didn't get a failed delivery message. Might be in your spam folder. I will send it again now.
Many thanks again.



Edited By Tony McC on 1571035491

[Tony McC]

Grrr! Why have you published my *private* email address on a public forum? Very, vert bad and completely unacceptable!