# stain removal in limestone.



## JArgabright (Aug 1, 2013)

Thanks for reading. We are cleaning a 90 year old home. This has never been cleaned before. Black organic stains are very heavily saturated in many areas of this home. We have used many products and testt samples, none of which will penetrate deep enough to fully remove stains. Other areas of limestone still have heavy streaking and discoloration from decades of water and grime. I'm hoping to get a few different opinions of some success others have had. We have used hot water pressure washer along with several chemicals(suggested by our Prosoco rep) these meet my expectations, however owner is looking for better results. I'd love to achieve their expectations.


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## Live_oak (Jul 22, 2013)

I'm assuming that this is flooring? 

It's labor intensive, but have you tried a stain removing poultice like you would do for a stone countertop? One recipe that my stone pro recommends for marble is 30% hydrogen peroxide (like you'd get at a beauty store) mixed with baking soda into a paste. Apply to the stain, cover with plastic wrap and let sit for 48-72 hours. I've seen that work on severe red wine stains and other things that you wouldn't think would come out of marble. I don't know if that would be too much considering the square footage that you might be dealing with, but it might be worth a test spot for you.

On reading this again, it sounds more like exterior cladding. Not sure how a poultice would work in that situation, but perhaps the peroxide might still help?


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## JArgabright (Aug 1, 2013)

We are using a poultice on the interior wall where a roof leak had stained limestone for several years. This poultice pulled the dark stains out but left. The outline and shaded area behind. I will see tomorrow how the 2 nd application turns out. All this limestone is, or was a sanded limestone. All but 40 SF is exterior. windows surround, coping and transitions are all sanded limestone. All other exterior is natural blue vein stone. Having never been cleaned is making this exceptionally hard to achieve optimal results.


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## dom-mas (Nov 26, 2011)

a baking soda paste can help but really you're just peddaling nowhere. stone is very diffiult to clean. Prosoco is a good company, when what they offer fails, there's not much left besides mechanical cleaning which does a lot of harm.

Limestone absorbs water borne contaminents so whatever you use needs to include water to get those stains back out. Difficult inside.


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## j_sims (Jul 5, 2007)

I've had pretty good luck with on a couple of limestone projects using soda blast...One was done with Kiserite(sp) due to a lot of foliage around the building.


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## dakzaag (Jan 6, 2009)

If the Prosoco products are not sufficient then you are down to mechanical means. 

This is never recommended as you sacrifice material for looks. The only consolation is the stone is full thickness so there is no veneer so to speak except for the stain. The stain can run pretty deep so you may end up having to mortar patch over the stone to keep it smooth. 

Mortar patch will probably be just as obnoxious as the stain which leads you to full stone replacement. 

Hope you are a good educator as your customer sounds like they are a little dense and are expecting impossible results. 

The limestone cleaning products from Prosoco continue to clean for months after the initial application resulting in a more satisfactory result a year or two later. Also with heavy staining, several applications with months of time between will improve results. 

If it took eighty years to get this bad, an overnight fix is unrealistic. Educate your customer.


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## jamestrd (Oct 26, 2008)

dakzaag said:


> If the Prosoco products are not sufficient then you are down to mechanical means.
> 
> This is never recommended as you sacrifice material for looks. The only consolation is the stone is full thickness so there is no veneer so to speak except for the stain. The stain can run pretty deep so you may end up having to mortar patch over the stone to keep it smooth.
> 
> ...


 
I have the same problem with the limestone at my house..living there 10 years, the last 4 years or so, I can not clean it either, however it used to come clean every spring when I power washed..I skipped a couple times, and now impossible.

I wonder if a sand blasting could do it..


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## dakzaag (Jan 6, 2009)

You really want to avoid removing material if at all possible. The Prosoco products do a great job of removing many years of staining.

For reference the normal rate of decay for limestone is 1/16" inch every 100 years. If you mechanically attack the stains, you are likely to subject the stone to 100 years of decay in about 1 minute of sandblasting or whatever process you use.

The chemical process from Prosoco accomplishes the same thing without removing any of the material. I have never seen any stains that did not respond to the limestone pretreatment, cleaner solution and nutralizing product from Prosoco. It is essential to follow the application instructions to the letter as the products are very specific in there mode of action and effectiveness.


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## Ohteah (Apr 3, 2013)

I know this may be of no help, but I cleaned limestone pillars at the Corcran Art Gallery in Wash,DC couple years back. We used a product you brushed on, it was like a big laytex condom. You brush it on according to specs and let it cure. When it fully cured you just started peeling away,came off like a giant rubber. I'm pretty sure it came from Germany. It was recommended by our Jahn dealer. I know helpful, right? wish I could remember the maker, I'll try to figure it out. Worked well, took two applications and I believe it comes in different concentrations, it was a 2 part mix. Cleaned the details of the scrolls and the flutes great after 2 shots


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## Kowboy (May 7, 2009)

http://www.klenztone.com


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