[larhonda2000]

There's a lot of black stain on some patio stone contracted to seal. It's old stone, probably 20 years old.

I have tried the following products to soften the black. I don't know if it is tree sap, some type of mold or what but nothing works!!

Bleach, ammonia, mean green, borax, TSP, vinegar, wd40, baking soda, vegetable oil, goof off, goo gone, paint thinner, I think that's all I've tried. NOTHING!!

Hope someone can help me!

 

[RH]

Not my area of experstise but I have some of that stone at my house. I have just let it weather and am fine with the look (never been sealed), But if I did want to try and fix it I'd contact our local stone and paver supply outfit to see what they might recommend. Perhaps a product designed to etch concrete, such as muric acid, might do the trick. But I would test it in an out of the way place first.

 

[jennifertemple]

Resourses I found on YouTube:
Smart Seal Products are sold in the USA exclusively by Leslies Poolmart Inc. through their 700 locations

 

[stelzerpaintinginc.]

If it's organic, bleach. If not, sodium hydroxide or EBC. You said you used bleach, but you didn't say at what concentration.

Also, if you're not a professional painter or pressure washer, it'd be best to post in our diy forum.

 

[larhonda2000]

I am professional painter, yes. 6 years. I haven't ran across a stone I couldn't get the black stain removed. I'll try the sodium hydroxide. Thank you

 

[stelzerpaintinginc.]

I am professional painter, yes. 6 years. I haven't ran across a stone I couldn't get the black stain removed. I'll try the sodium hydroxide. Thank you

What percentage bleach did you apply? Although sodium hydrox would work no matter what, that looks like it would come right off with 3%-5% bleach after a short dwell time.

Are there trees above?
Does all of it look like that?

 

[larhonda2000]

I replied within your comment body. Look for the asterisks****

What percentage bleach did you apply? ****Concentrated bleach from Walmart //

Although sodium hydrox would would no matter what, that looks like it would come right off with 3%-5% bleach after a short dwell****dwell time was 15 minutes. Didn't touch it.

Are there trees above?****yes
Does all of it look like that?****no, mainly near areas of moisture (e.g. near water fall from roof or places where water puddles//

Thanks for the reply!

 

[MeMyself]

Can you mechanically remove it? Wire brush?

 

[larhonda2000]

Can you mechanically remove it? Wire brush?

I'm geared and ready for that today. Not a wire brush but a rotating cleaning attachment for my drill. Hoping it'll work with the chemical to loosen from the pits. Thanks for suggesting. I'm on the same page lol

 

[MeMyself]

I'm geared and ready for that today. Not a wire brush but a rotating cleaning attachment for my drill. Hoping it'll work with the chemical to loosen from the pits. Thanks for suggesting. I'm on the same page lol

If that works okay, but is a pain in the ass, a wire wheel on a grinder will be easier. If you're buying a grinder, get corded, not cordless. I tried 3 different cordless ones on one job before I ended up just buying corded. Batteries all overheated.

 

[kmp]

If you use a wire brush or wire wheel on a drill or angle grinder use a brass bristle and not a stainless steel one as the steel can leave black marks that can just add to your problem.

 

[jennifertemple]

I am professional painter, yes. 6 years. I haven't ran across a stone I couldn't get the black stain removed. I'll try the sodium hydroxide. Thank you

That's why an introduction post helps. The mods can not readily tell if a poster is a pro, based on the first question a body asks. BTW: Great to see another woman on the boards!!
Welcome to PT!

 

[larhonda2000]

That's why an introduction post helps. The mods can not readily tell if a poster is a pro, based on the first question a body asks. BTW: Great to see another woman on the boards!!
Welcome to PT!

I didn't receive an email packet explaining for me to do an introductory post. I just know to go where my brain leads me- to read posts and learn. Thanks for the nice words. I love to paint. Always have loved to paint since I was a kid. Figured I'd start a business-it's going great!!