Black ?Mold? on rock house????

[dcoronado 19]

Hello to all,

My name is Daniel and I have about 4 months experience in this type of work :)

I have been shadowing a friend who has been doing this for about 12 years but would also like an opinion on what this is.

I did a rock house (lower half) with stucco to upper portion of house. Anyway, on the rock portion there was one rock that was covered with black stuff - mold I thought. I hit it with 1:1 bleach about 8 times to no avail. I am using a 5.6 GPM with hot water and 3000 PSI. I then progressed to make the bleach stronger and still to no avial. I then placed bleach straight to no avail. It did get better but after about 12 applications it is about 75% less than when I started.

I also used Zep commercial all purpose cleaner.

Here are the pics.

What else do you recommend...I would like to get it all off.

Oh by the way I left the rock with straight bleach soaking over night.

Thanks,

Daniel

[PressurePros 249]

It looks like an end cut from which you removed a colorant coating

[Washaway 64]

could also be oil deposits in the stone itself. Had a client who bought cheap flagstone and he found out why it was cheap after it was layed around the pool.

Bit of degreaser pulled it all out.

question is why only that one stone...or are there more of it's kind?

btw, that looks like it's a piece from an entirely different batch.

[Adrian 155]

... or it could be a core section from a larger stone that has ions of mineral deposit buildup. The deeper you dig the more you expose. Texas has layers of cleeche SP? before you get to any layers of solid rock.

Cool to see another lone star on the board.

[Beth n Rod 1,279]

Welcome Daniel! :groovy2:

Beth

[A and J POWERWASHING 64]

if it was mold it would have came out , it might be some type of mineral in the rock it might just be a you have to live with it thing some time that sucks

[slightmold 64]

Does the home owner or maybe a local know what type of rock this is ? It maybe native to the area...or maybe not.... I'd try to find out the type of rock and google it.... Somebody has to have an answer...Also.. how old is this house ? You probably let us know....I'll go back and check.... Welcome aboard.... I hope we can help....good luck and let us know.. what happens...I love rock on the base line of a home...heck.. I love rock period... marvin

[dcoronado 19]

The area was all black when I started and after multiple applications of bleach and zep it did begin to go in some parts from black to gray. Other areas begin to show the color of the rock. What is left is what would not change back to match the remainder of the house and those parts stayed gray or black.

There is another stone that is like this but no where near this bad. I could not get the black off of it either. It to now has gray or black mixed with the original color of the house????

The house is around 5 years old.

Will see if I can find out what type of stone it is.

Thanks,

Daniel

[Tmrrptr 164]

Hello D,

Doesn't look too bad to me, (I like to tell people God made it that way), but you might try some phosphoric acid and let it set a bit before rinse.

r

[Beth n Rod 1,279]

Good morning Marvin & Daniel,

Please go to the User CP and add your signatures. Thanks :)

Beth

:cup: ...a good day begins with coffee :cup:

[hoosierwindowtek 14]

I'm no expert on stone, but that looks like granite or something, and you're not going to remove the color of that.

Maybe they mixed in the wrong type of stone when they built the wall.

[dcoronado 19]

Well thanks to all for the information. I did speak with a technical advisor from a chemical company and he states that it is Quarry Sap and it is a natural part of the stone. He also states that no chemical with change its appearance.

AC New Guy, also glad to see someone from the Lone Star State. E-mail me, I go to Houston on occasion. My e-mail is Daniel@mrpowerwash.us.

Thanks again for the advise and input,

Much appreciated :)

Daniel

[Tmrrptr 164]

Wow!

See? There is the value of BB forums...

I never, ever, heard of quarry sap, before!

Thanks

r

[Lightning Gene 66]

"AC New Guy, also glad to see someone from the Lone Star State. E-mail me, I go to Houston on occasion. My e-mail is Daniel@mrpowerwash.us."

Welcome Daniel from another contractor from the GREAT STATE OF TEXAS

[Adrian 155]

Gene,

Don't you mean "Great Nation" of Tx.

( sorry .... couldn't resist)

[James 625]

The photo shows exposed granite. The pressure took off the top layer. The Brown spots are from iron in the granite leeching out.

[dcoronado 19]

Lightning Gene, thanks and glad to hear from you.

[dcoronado 19]

The photo shows exposed granite. The pressure took off the top layer. The Brown spots are from iron in the granite leeching out.

So James from the picture and well the house (not full view in picture) the surrounding rocks is what the majority of the house looks like. Except for about two rocks in which the initial black stuff came off slightly after being aggresive....maybe I was to aggresive?

Is this top layer artificial or a natural part of the rock?