I was wondering if using a SH mix on natural slate would discolour it any way ?..If not what ratio would you be looking to use?..I am in the uk but i imagine slate is slate .
Thanks
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Thank You Thad…I have been lurking for a while but time to get active !
My slate experience is minimal but the big thing is to not use soap or a surfactant in your mix.
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But a sodium hypochlorite mix is the way to go, yes.
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What does the soap/surfactant do to the slate?
I’ve never done one, but there are several threads that discuss it…Sounds like the surfactant really discoloration and/or leaves a residue that won’t come off.
Jesse
Atlas Services
Exterior Cleaning Specialists
North Carolina
Bringing back an old thread here. I have a slate patio coming up and was wondering if there were any rules to follow to remove heavy organic staining. My inclination is to begin with inconspicuous test spots, slowly working up the sh concentration. On Flagstone sometimes I will go all the way up to pure undiluted 12.5% to get the deep black stains out. However I’m nervous about doing that on this I’m not even sure if 4% to 6% will be safe? Is there any other specialty products that should be used instead?
I can’t answer your question on the SH, just make sure your tech doesn’t use any high pressure or sever angles as slate tends to sheer and pieces will lift off. You can see it on that patio already happening, and some pressure will make more sheer off. I would definetly put it in my verbal and written stuff that it is inevitable that some will sheer.
Flagstone can be from slate, slate and shale aren’t that far apart. I hope you got a dolly, those pots filled with dirt are gonna be heavy, but you got to get your flex on so there is that.
Good luck. Post some after pics, those will be nice before/afters for your portfolio. That will look so good cleaned up, except for the tiles that are crushed. soft wash and rinse.
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Blue slate, like shown in some of the pic, SH is fine, most I’ve ever needed is 2-3%. SC around 2000.
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Since it is so delicate I may want to try 4 to 6% and 1000psi rinse tip at 65 degrees. Do you think that would be too hot of a mix for it?
Will do thanks man! I forgot to put a note in the proposal about having them move the pots. Looking forward to the after pics myself
Not that dirty, 2-3% should clean fine. All your doing with the SH is killing organic stains. Less chance of damage with a surface cleaner, the pressure hitting straight down rather than at an angle.
Funny that I saw this. Just ran into some myself today. Got hoodwinked on a house wash and patio that was considerably larger than anticipated.
There was definitely some shearing. Don’t know if I’d be
down to do it again without written contract .
Looks good! Go ahead and SH those boulders for them while you’re there…lol
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I have a 4 tip bar and I will try putting one 4.5 and one 5.5 orfice tip on each side ( I only have 2 of each) that will give me the equivalent of a size 20 tip and on 8gpm will put me at about 1000 psi. I’ll use high heat too. Pre-treat 3% and post treat with 3%. The concern for needing to do all this is there are deeply embedded stains from the oak tree and standing tapwater. In my experience the only way to get those deep stains out (in Flagstone at least) is to use a very high concentration of SH. Typically for flagstone my process is to use high heat and full pressure followed by straight 12 1/2% application of SH and allow to fully dry. Then do a final rinse. With this process it’s is no longer a cleaning it is a full restoration making it look brand new.
Lol. I would if I have 12.5SH.
I’m stuck using Clorox at 7.5 until I can (afford to and use in a timely fashion) order 275 gallon tote which will be a 2200$ to get to me. Until then it’s Costco 3 packs 
As in shearing sheep?
Why do you come on here asking advice and then always go do something different? Asking for a friend.
Was enough moss that that could probably considered shearing like that haha.
Like 1/16 of an inch of the tops were wanting to separate. Shale/slate and I don’t seem to get along. It’s been the bane of my existence with my first house. There is a garden that Mrs. Dalls and I like to work on and as we started digging around noticed that there was an entire rock garden of the stuff just buried below. I’m talking huge flat chunks. Thousands of pounds of it. Every time we put a shovel in there we seem to find more of it. We used it to create a little rock wall against our grass. I’m going to be honest, if I never saw another piece of that stuff again in my life it would not bother me one iota. 
