Removing Stains from Stone

[fineline]

Its been a while since I've been on the site, but I just bought my first house that needs A LOT of work so I'll be spending plenty of time here again. My first problem is staining on the fireplace surround. As best I can tell it is water-stains because the flashing is failing at the chimney roof penetration (yes the roof is leaking).

Is using poultice the best way to get these stains out, and are there any ways of telling just what caused the stain -- could rust from the flashing also be a culprit? I just want to make sure I use the right chemical to remove the stain.

Also -- does anyone know a good reference for determining actual stone types. Is this limestone? All my searches just lead me to marketing names like "Rustic Country Cottage Stone", "A River Runs Through It River Rock"

Thanks for your help.
Sean

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[opiethetileman]

Hang tite one of the stone ducks I am sure wil drop in if not PM granite girl and see what she says shes got a lot of knowlegde in her head on stone.. They might tell you to seal the whole thing i dont know see what they says. that looks like man made brick.

[Tool Guy - Kg]

Hi Sean,
Let me move this over to the Cleaning, Restoration, & Sealing Forum for you. Hang tight...

[GraniteGirl]

Looking at the picture, it looks like it might be sandstone. Does the stone have a grainy, sugary texture?

It is difficult to say from the picture. Is there any way to get close-ups of the stains?

[Stonehenge]

Hi Sean,

Take a white cotton towel and rub the effected area to see if there is transfer, more than likely if there was FeO2 precipitant this would be an indicator.

You can also wait until the next rainshower and feel the stones' surface for moisture.

Michael

[Stoneguy]

The picture is kind of grainy, but I'm about 99% sure what you have is Tennessee Sandstone split face strip rubble. I can't seem to find pics of this exact cut of TN stone, but here is a picture of some sawn tread stock of TN stone:
http://www.irwinstone.com/PhotoGallery/images/Specialty_Tennessee%20Sills_jpg.jpg

This stone will stain pretty easily, as it is very absorbant. You first need to solve the conditions that are allow the water to get in. Then you may be able to poultice out the stain.

Do NOT use acid on this stone. Major funky discoloration happens if acid is used. I think a good stone specific detergent like Lithofin SCS mixed into a good poultice median would be the first choice of attack. If the stains are actually from rust, cleaning is a bit trickier.

I have heard many stone restoration folks talk about using Iron-Out. No personal experience on this one, perhaps others will comment.

I use a great combo of chemicals here in our shop for rust stains. They are somewhat tricky (and hazardous) to use, and difficult to buy, so I'm not inclined to recommend them in an open forum. Try the basics first.

[fineline]

wow - I'm always amazed at the wealth of information available at this forum.
- GraniteGirl - I haven't closed on the house yet, when I do I can get back in and get a better picture. If I remember correctly it wasn't too "sugary", it was fairly smooth (100 grit sandpaper I guess) and a bit dull in terms of sheen.
- Stonehenge/Stoneguy - do you think water alone can cause these stains, or is it likely the water is picking up some rust as it works its way down from the roof? I already know the flashing is failing and that is where the water is coming from, once I fix that I'll try the cotton towel test and report back. I have run across some positive comments about Iron-Out so maybe I can give that a try once I determine the exact cause of the stain.

I caught Ask This Old House this weekend, and they had a bit on removing stains from stone countertops using poultice, they never mentioned covering the poultice with plastic as I have read is the correct way to do it.

Thanks again!

[Davestone]

It may be iron, but it looks like it could also be wood resin, or roofing asphalt.In any case,you need to stop the leak, and do as suggested to see what removes it,try different things.Iron out is acidic, but sandstone isn't harmed by acids,but it may set the stain, so blot in a small area.You may also try a plain old alkaline stone cleaner first,on a piece, or stone soap, and a soft brush, a stiffer one may wear away the stone,if it's been damaged.Here's a link that may help...http://www.baneclene.com/Stone_Care_Guide.html