# New to the profession, questions?

**URL:** <https://pressurewashingresource.com/community/t/new-to-the-profession-questions/10493>\
**Category:** Residential\
**Created:** [December 7, 2017, 4:08am UTC](https://pressurewashingresource.com/community/t/new-to-the-profession-questions/10493 "2017-12-07T04:08:51Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![tireshark](https://pressurewashingresource.com/community/user_avatar/pressurewashingresource.com/tireshark/32/6402_2.png) [@tireshark](https://pressurewashingresource.com/community/u/tireshark)\
**Post date:** [December 7, 2017, 5:03am UTC](https://pressurewashingresource.com/community/t/new-to-the-profession-questions/10493/4 "2017-12-07T05:03:29Z")

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> [@BK\_Bill](#):
>
> Forgive me I should have been more specific.
> 
> I am mostly referring to old stone, brownstone/ limestone. i have not found sufficient info through google.  
> This stuff is delicate old and expensive. Wondering if anyone has had experience with it and what did they use to not “damage” it.

No offense, but what was more specific about that? It’s the same thing you said in your first post. My answer is the same… I found all these threads in about 5 minutes, two were from this forum, and there were others from here i didnt link.

Search google for pressure washing forums, then go to each one and type ‘limestone’ into the search bar. That’s the best way to learn the basics, IMO.

> [@Black stains on limestone columns, pedestals- how to clean?](https://pressurewashingresource.com/community/t/black-stains-on-limestone-columns-pedestals-how-to-clean/1633):
>
> I’m starting a big job tomorrow and some of the mess consists of limestone features around several terraces. they are columns, pedestals, caps of retaining walls, etc. they have that black algae look. I know that stuff can get embedded deeply into limestone due to it’s porous nature. i also know that drilling it with high pressure can really beat up the surfaces. sorry, no pics yet, i can post some tomorrow. any tips on how to lessen the appearance of the black discoloration? should i jus…

> [@White Austin rock with black stains?](https://pressurewashingresource.com/community/t/white-austin-rock-with-black-stains/9824):
>
> Hey folks, I’m on this project and I cannot for the life of me get this black stuff to go away. I’ve tried downstreaming 12.5% sh with eliminator, I hit it with pressure and yet it’s still there! I’m about to get a ladder and apply the sh straight to each rock… What do yall think?

[http://www.ptstate.com/forums/showthread.php?2055-Anyone-ever-cleaned-limestone&highlight=limestone](http://www.ptstate.com/forums/showthread.php?2055-Anyone-ever-cleaned-limestone&highlight=limestone)

[http://www.ptstate.com/forums/showthread.php?7769-Cleaning-limestone&highlight=limestone](http://www.ptstate.com/forums/showthread.php?7769-Cleaning-limestone&highlight=limestone)

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