# Epoxy prep question



## JonM (Aug 3, 2012)

Hey guys,

I've got a question here that I know you guys can help with. I have searched the forums already because I figured I'd find the answer but didn't.

The problem: 
I just epoxied an existing garage floor for a client. There were two old oil stains on the concrete from the previous owner's vehicles. I asked at SW when I picked up the product whether the oil had to be removed and they said no, it won't cause a problem. I should have been smarter than to believe the SW manager as I know how crucial surface prep for epoxy is. As I was rolling on the epoxy I noticed that as I back rolled over top of where the oil stains were, the epoxy would lift right off in small spots and I would have to re-roll the area. Now I am assuming that I will get failure in those two areas down the road due to lack of proper adhesion. My question is, what do you guys use to remove the oil contaminants on an old garage floor?

My prep:
We did a thorough application of muriatic acid to the floor. We power washed it off along with the other dirt that may have been on the floor. We made sure to blow out any dirty water and used a broom to remove any pooled water. We let it dry for 4 days and came back and repeatedly swept and vacuumed the area until we were sure it was free of dust and dirt. We brushed and rolled the epoxy and used SW Armorseal 1000 HS.

I know some say muriatic acid is not the correct prep period and it should be diamond grinded, however, both my Dulux and ICI reps have said the acid is an acceptable method of prep.


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## ewingpainting.net (Jun 2, 2008)

Grinding is the best way to prep a floor. Muratic acid is like 1980s, would never even consider using a acid etch

...


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## ReNt A PaInTeR (Dec 28, 2008)

Lol. You trusted someone from Sherwin Williams.

It's your fault


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## ReNt A PaInTeR (Dec 28, 2008)

One time one employee told me I needed a gallon to do 6,000 sq.ft of cedar fence but to buy 2 gallons just in case.


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## kdpaint (Aug 14, 2010)

Acid etch=fail. Grinding is actually easier IMO. Less steps, less time, better results. Acid is a PITA that doesnt work well. It is a no brainer.


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## JonM (Aug 3, 2012)

Thanks for the feedback. I know, I'm an idiot. But my question was whether you all use anything aside from grinding to remove oil stains. I wasn't trying to debate acid vs grinding.


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## Epoxy Pro (Oct 7, 2012)

Never listen to the paint store guys, infact never listen to the SW rep unless he has been around for a very long time, our SW store and rep said the same thing, our BM rep said grind do not use acids, we listened to the BM rep. Yes grinding is the way to go, for stains on the surface I let the grinder sit on them for a few seconds moving it side to side, back and forth over the stains.
I am positive you will be back there with in a month or 2 to fix the floor, this is a costly mistake, depending on how long the HO doesn't drive on the floor or if he drives long distance and parks right on the floor with in the first couple weeks it will fail.


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## NACE (May 16, 2008)

Jon

There are enzyme based degreasers that actually feed on hydrocarbons. They work extremely well. They actually penetrate into concrete rather then treat the surface as most heavy duty degreasers do. They are microbial degreasers that are exceptionally effective and do not add prep time to the job. 

Regrets that the advice given and followed was not to worry about oil. SSPC-SP-1 is always the first step. 

Here are the steps I take for a residential garage floor. Not in order always. 

Test for curing compounds

Test moisture content

Test concrete hardness

Review customer expectations. 

Degrease and power wash. 

Diamond grind to surface profile of CSP-3. (50-80 grit sandpaper)

100% Solids Primer

100% Solids Intermediate or Polyamide Epoxy. (anti-slip or vinyl chips)

Acrylic Urethane Clear coat 

Sometimes I will switch to waterborne amine color coat and waterborne aliphatic clear coat depending on odor concerns.


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## JonM (Aug 3, 2012)

Yes, costly mistake indeed. I appreciate the advice and understand the benefit of grinding to get that required profile. On the plus side, this is a 450ft garage floor in an older house and it's better to learn the hard lessons here than a 4000 sq ft. commercial space. Of course I will have to leave the owner happy, which will definitely cost a few dollars. 

Lesson learned.


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## WisePainter (Dec 27, 2008)

Shot blast, or diamond grind.

Concrete is so soft these days to cut costs that heavy acrylic applications can lengthen grind times to a stand still.
I drop water following the grinding and smear it with my toe.
If it sits, regrind.
If it soaks in, proceed with prime coat.


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## Epoxy Pro (Oct 7, 2012)

I do a moisture test, tape plastic in 5-10 places for 24 hours, if it's dry it's good to go, if it's wet there is some moisture issue that must be resolved or failure is a guarantee.


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## bskerley (Apr 15, 2011)

Unfortunate that you did not neutralize the acid.


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## Jmayspaint (Mar 26, 2013)

Another epoxy prep question; can you not just take digital moisture readings to make sure a slab is dry enough? 

When I was doing my first epoxy job, I could not find a reference in the literature about acceptable moisture content. The SW rep would not give me a number either. The plastic test was all that he would recommend/ accept as valid.


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## NACE (May 16, 2008)

Jmayspaint said:


> Another epoxy prep question; can you not just take digital moisture readings to make sure a slab is dry enough? When I was doing my first epoxy job, I could not find a reference in the literature about acceptable moisture content. The SW rep would not give me a number either. The plastic test was all that he would recommend/ accept as valid.


I have a Tramex Non Destructive Moisture Encounter. It is the best $450 I ever spent on a test tool. Generally concrete will stabilize and acclimate to 2.5-4% moisture content. Older floors before code required a vapor barrier can be tricky. Concrete may be dry in summer but 8% in spring. I learned the hard way on 120,000 sq ft warehouse floor. Point is test concrete for a % of MC and photograph the meter with the date. I test after I grind and keep a record. If there is a failure there is a record that at the time of preparation and application the MC was within acceptable levels as by the ICRI. International Concrete Repair Institute. Doesn't matter if you are doing 450 sq ft or 120,000 sq ft. Test, verify, and record. Acid attacks electrical. It turns to salt water as soon as it comes in contact with concrete. DO NOT USE ACID TO PREPARE CONCRETE FOR A FLOOR COATING. Call me if you have questions. Only time you can't call me is if Christmas Eve falls on a Sunday and it's midnight. Otherwise I'm good.

Sent from my iPhone using PaintTalk


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