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Iron Oxide ???

Hi all, I have recently completed a project using Porcelain paving from London stone which we grouted with Ardex Flex grout and laid a head edge of granite setts.  

Due to the customer wanting to purchase the tiles and grout we ended up having to lay the lawn prior to grouting ( as we had to wait for the grout and they couldn't get enough of the tiles in one hit).

The grout and tiles arrived so we could complete and clean up.  I noticed brown marks on the granite which I thought was just sediment from the new lawn as both patios run towards it.

The setts will not come clean.  I've been trying Lithofin Bero (initially at the recommended 1:10 to no avail.  Over a few days I have been strengthening it to eventually trying it neat.  Still no good.  

The grout company is adamant its Iron oxide whereas the granite supplier is blaming the grout even though the stains began prior to grouting.  

I've tried explaining that I'm not out to get any refunds or compensation.  

I just want to get the job right so I can invoice.  

If this is Iron oxide I have never seen this so prevalent in any natural stone in 20 years.  Any thoughts?

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Replies

  • PRO

    In my experience Richard, if it's iron staining then there's very little that will shift it.

    Have a look at these two threads.

    Paving expert: Removing stains

    LJN: Stains on sandstone paving

    My initial thoughts were that the iron may have come from the turf but it's clear to see that the staining emanates from the paving side rather than the lawn side.

    Pavingexpert - Maintenance and Repair - Removing Stains
    Hints and tips on cleaning stained pavements
  • PRO

    Last year we had a problem where we had some fertiliser with iron go on some very expensive stoneworks, and couldn't use any chemicals to remove. So used small amounts of pure freshly squeezed lemon juice direct onto the stone, leave for 5-10 mins and good go at with small hand scrubbing brush. Rinse off with plenty of water. Repeated 3 times. Worked well. May be worth trying on a small test area to see if any impact.

  • You could try Oxalic acid, it's found in Rhubarb leaves.

  • PRO Supplier

    The pattern is very obvious. It's not coming from the turf or fertiliser that has been applied to the turf. 

    It also doesn't look like the grout is stained to the same extent.

    Did you use some kind of wire brush to remove grout from the surface of the granite? Is it possible the wire was steel or iron? Possibly not but just a theory.

  • PRO

    It would be good to know if this staining is prevalent on edging stones where there is no adjacent turf.

    • Hi all, I have tested the grout on an unlaid sett, no discolouration so far. I also have one sat in some wet soil from the same supplier. No Pre turf used as we have had staining from it on paving before. I also have setts running up either side of the lawn with no paving butted up to it. These all seem fine ?????
    • Hi all, I have tested the grout on an unlaid sett, no discolouration so far. I also have one sat in some wet soil from the same supplier. No Pre turf used as we have had staining from it on paving before. I also have setts running up either side of the lawn with no paving butted up to it. These all seem fine ?????
      • PRO

        Did any water used in the laying / grouting /cleaning process have a high iron content ? 

        • Unless it's from the grout it was just standard tap water so doubtful. I'm gonna try some oxalic acid on it tomorrow
  • Hi all thanks for all your posts.  I have tried Oxalic acid and it made no difference at all.  The MD of Global stone contacted me and because of the products I have tried and their effects he reckons its not iron oxide but hydrochloric acid staining.  I definitely haven't put any other products on the patio other than Lithofin builders clean at the recommended ratios and Lithofin Bero on the setts to try and remove the rust stains.  The Global Md said that the Bero product would make it fizz if it was iron oxide (which it definitely didn't).  So a trip to the suppliers tomorrow to buy some more setts and rip the stained ones out.  I'm gonna pre seal these puppies and hope for the best.  Anyone with nothing to do this weekend is more than welcome to join my Granite sett party ;-)

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