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Discussion Starter · #1 ·
I went and looked at a job tonight, cultured stone over a freshly poured wall, the wall looks great, super slick and vibrated well, my concern is any form oil residue though.

I have done a ton of cultured stone over wood framing and CMU, but I realized I have never actually tackled one over a fresh wall.

The guy asked me about using mesh and I told him that with a CMU wall it is basically useless, but with a wall that has been painted or possibly has form oil it might be cheap insurance. It will add a few bucks per foot though, and tapconning that lath will surely suck.

I know this has probably been discussed before but I couldn't find it.

Will a pressure washing and maybe an acid etching be adequate? I really don't want my work falling off the wall later.
 

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Ive gone over foundations without worrienging about it. They stick. I suppose you could scrub it with a broom and some sort of cleaner or power wash it.
 

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Discussion Starter · #3 ·
If it was aged I probably wouldn't worry about it, but it hasn't even seen a rain storm yet. I don't know much about the company that poured it, but I know the guys I help occasionally marinate those forms with oil, gallons and gallons of it each job, the stuff has to be sitting in the surface of the concrete somewhere.

I guess some sort of detergent would be better than acid huh. Maybe simple green.
 

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Call the company who makes your thin stone mortar, they will know more about it then us dummies.
 

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Shouldn't it be at least 28 days old? I don't know, just curious..
 

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Was thinking more for moisture/efflorescence..
I know for staining/sealing most manufacturers spec at least 28 day
 

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About four years ago I was called to look at job where the mason installed cultured stone directly over a recently poured concrete wall. The mortar did not bond to the concrete and the stone was literally falling off in 4' to 5' sections at a time. (this home was about 3 years old) I think the wall was about 10' high and about 30 or 35' long. I removed what little stone there was left on the wall (with ease) applied mesh with tapcons and washers, scratch coated and installed new stone. I really think that mechanical bond will be stronger than just etching the wall. May be a bit more work, but at least you'll only have to do the job once.
 

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Renaissance Man
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I would wait for the full cure from a moisture and bond concern as well - lath, I wouldn't be as worried.

If you're avoiding lath, hot water and Dawn detergent, power wash, some strong muriatic, power wash and rinse again.

A good solution here would be to burn in a notched trowel coat of a good exterior thinset and allow to cure. It's quick and easy to do and provides a nice key for your bedding mortar.

A cheap way out is straight Portland slurry coat with a tampico brush dabbing technique to provide some texture.
 

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Always Learning
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Worst case you could pressure wash and then hit with a bonding primer before you scratch coat.
 

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Have Trowel, Do travel
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most of my masonry work is on concrete, If you are that worried, rough up the surface by hand or mechanical means, I just got this

Then use a thin-set. I use mostly keraflex maxi S1.
 
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I'd be paranoid too. I like mechanical bonds a lot. Rough substrate is what I would want. if it's real fresh still tapcons should just sink in, but yeah add $1 sqft for lath and mortar and a day for the extra time
 

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The wall contractor would have used some sort of form release; Yes that needs to be removed as it is just as effective to release the bond from the back of the stone. Check with your stone mfg you will use; I suggest vendor for masonry cleaning.

Also, wall needs time to release the excess water/chemicals that were added at batch plant to redi-mix truck, to make concrete a useable mix. Thus 28 days is also a good rule of thumb for initial moisture dissipation. If you cover concrete with VCT's, carpet, hardwood, manufactures of those products and mainly the adhesive to attach them, there is a certain moisture content allowed, if not the moisture wants to push through and debond what you are trying to adhere.

So, just to be on the safe side , cleaning the wall at any point , and letting it sit for at least 20 days before starting your project. I also support superseal and overanlyze suggestion for a bonding coat of your choice
 

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ok brunothedog, I will bite (no pun intended) what brand is the handheld unit? Is it a scarifier? Or what type of profile unit would it be?
 

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ok brunothedog, I will bite (no pun intended) what brand is the handheld unit? Is it a scarifier? Or what type of profile unit would it be?
a scarifier its called i guess.
i know it as an eletric bushhammerer
i have no ideal about the brand,,its made in germany.
i got 2200sq.ft of concrete to bite into
 

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Just my .o2 cents. What JBM proposes will do the trick ,what Tscarbourgh proposed will definitely do the trick. If the forms were wood and saturated by oil,much dusting will occur on the poured walls. If they were steel or aluminum, they could come out super slick. Then I would definitely do the sand blast.
 

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Discussion Starter · #19 ·
I talked about it with the guy and we decided to tapcon and lath it.

To clarify, it was poured before winter, but the ground was starting to freeze right when they back filled, so the wall has barely weathered yet, it is just beginning to turn into rain season right now here.

Either way, it's only about 400 sq feet and I told him the extra cost would be cheap insurance if the chemical bond didn't take due to oil.
 

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Spiderlath over concrete stem wall

Spiderlath was called for in the plans for cultured stone exterior on a 10' high 300' long concrete stem wall. It was installed 8 years ago with no problems to date. The location of the project was Mt. Hood in Oregon.
 
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