Staining - Stains on newly laid fossil mint

[BobButler]

I have laid about 30m of fossil mint over Easter. We laid it on a full bed of sharp sand and cement and PVA'd the back of the slabs. It looked great for a while but I now have some horrible brown stains on some of the slabs. Any ideas what has caused this and what actions I can take to remove them please.

Thanks in advance, Bob.=145075722&filters[recent]=1&sort=1&o=0]My Webpage

[London Stone Paving]

Hi Bob

Can you post some pictures up on the site? would help

Steve

[BobButler]

Hi Steve, thanks for your interest, I've posted a picture for you. Bob

[London Stone Paving]

Cheers Bob

How long has it been since the stone was laid and when did the marks first start appearing?

Could be a few things going on

-Stone is full of iron deposits. Marks could be these coming out of the stone
-Moisture from the mortar bed, although if the slabs were primed properly then it shouldn't have be pulling anything through

There are chemicals available that can draw these things out but its not a guaranteed solution. I would wait a month and see if there has been any change

Steve

[BobButler]

Hi Steve, they appeared about 3 weeks after being laid. You mention priming the stones, what exactly do you mean by that? As I mentioned we PVA'd the backs following some advise relating to the stone having a tendency not to bond with the mortar bed. If these stains are iron deposits escaping (they look the right colour for iron) then is this commonplace and what are the products/treatment you mention to remove them?

Thanks, Bob.

[London Stone Paving]

Hi Bob

Yeh, its fairly common place. Your dealing with a natural material, its not always possible to predict if/when/to what extent things like this will occur.

I would leave it for a month, were heading into the summer now and I always think that warm weather can speed these things along.

After a month I would re-assess and try Lithofn Bero, its worked for us in the past as long as the issue isn't too serious

Steve

[BobButler]

Steve, thanks for taking the time and trouble to answer my query, I very much appreciate it. I will take your advise and gent back to you with the results. Very best regards, Bob.

[London Stone Paving]

No trouble at all Bob. This site has provided me with so much knowledge and information over the years. Always happy to share my own experience

Steve