# Paint did not stick to concrete



## workpot (Aug 28, 2008)

About 4 years ago I painted a small concrete floor (15x15) I used SW Tread-Plex floor paint after etching with muriatic acid. The area is usually a comfortable temperature, and is not driven on. It has not held up. It has cracked when I dropped a wrench on it, and then in some areas I just peel it up with my thumb nail once it has cracked, very little adhesion. Same is true when I slide things across it, e.g. lightweight furniture. 
I have removed the paint with a disc sander and 5” 3M Scoth Brite discs. While sanding the floor it seemed that the floor hardness varied as did the adhesion of the paint. Some parts of the floor I can scratch with a putty knife. I am wondering what happened here. It may be that the concrete mix was bad or at least inconsistent, or I did a poor job etching it or both, or because the floor varies in hardness, the etch varied. Or something I have not even considered.
Now the floor is baby-ass smooth. I am thinking about doing it all over, this time paying more attention to the etch, and using BM alkyd floor paint that I have used in the past (M22 073) I think. What about some thinned oil primer to penetrate before painting?
What do you guys think?


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## SWGuy (Jun 26, 2009)

Is there concrete stuck to the back of the peeling chips? Did you rinse thoroughly after acid etching? Did you perform a moisture test on the concrete prior to painting? These are just a couple of questions that I would have to try to figure out what is going on.


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## PaintMe201 (Sep 16, 2009)

m22 is not for floors... the oil based version would be 112... why don't you put an epoxy like garage guard on it instead.


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## workpot (Aug 28, 2008)

SWGuy said:


> Is there concrete stuck to the back of the peeling chips? Did you rinse thoroughly after acid etching? Did you perform a moisture test on the concrete prior to painting? These are just a couple of questions that I would have to try to figure out what is going on.


No, there was no concrete on the back of the chips. Yes I let it dry a couple of days, if I remember, I taped some clear plastic down overnight to test for moisture. I don't know if there is a vapor barrier under the concrete. And yes I rinsed it with water and shop-vacced it up twice. But truth be told, I rushed it and don't know if it was properly neutralized.


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## Picky Painter (Oct 7, 2009)

Sometimes the concrete itself is flawed. The worst mistake people make with pouring concrete is mixing in too much water. If mixed too thin, once all the water has dissipated the concrete will be weak and "honeycombed".


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## workpot (Aug 28, 2008)

PaintMe201 said:


> m22 is not for floors... the oil based version would be 112... why don't you put an epoxy like garage guard on it instead.


Yes, OK concrete is the back of the can (M22 73), but you are correct it's not a floor paint. However it is tough stuff and I have had excellent results on floors with it in the past. Yeah, sure I would try garage guard. Either way I don't think the paint was the issue in this case.


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## workpot (Aug 28, 2008)

Picky Painter said:


> Sometimes the concrete itself is flawed. The worst mistake people make with pouring concrete is mixing in too much water. If mixed too thin, once all the water has dissipated the concrete will be weak and "honeycombed".


If you are talking about 1"-2" honeycombed look that appears as a difference in shading, or looks like it is just below the surface, thats indeed what I have in some areas of this floor.


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## Workaholic (Apr 17, 2007)

Pot, Was this a DIY project?


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## workpot (Aug 28, 2008)

I dont understand, yes I am doing it myself. Am I a pro painter? Yes


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## Picky Painter (Oct 7, 2009)

workpot said:


> If you are talking about 1"-2" honeycombed look that appears as a difference in shading, or looks like it is just below the surface, thats indeed what I have in some areas of this floor.


The situation could be what i previously mentioned in my above post, another possibility is that the concrete got "overworked" in the finishing process. Some people dont know what a magnesium float is or why you are supposed to use it. When concrete gets too much darbying and trowelling, too much water is pulled to the top, leaving a weak top surface that isnt dense enough once the water has dissipated. It sounds like that's what you've got according to your description. Too much porosity can be just as bad as not enough.


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## Workaholic (Apr 17, 2007)

workpot said:


> I dont understand, yes I am doing it myself. Am I a pro painter? Yes


Yes that was my question, thanks. 
Once you determine that your concrete is ok then the best route but most work and expense would be to shave or grind a layer off of the floor and re etch and then apply a floor epoxy. 

Or as your OP mentioned you could remove any failing paint and smooth the edges and repaint with a garage floor paint. 
Of course if you have other areas that may fail then that could result in making the new coat fail as well.


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## bikerboy (Sep 16, 2007)

The plastic is to be left down for a minimum of 72 hours.

http://www.concreteconstruction.net/industry-news.asp?sectionID=715&articleID=259135


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## bikerboy (Sep 16, 2007)

The few we've done get sanded with 36 grit (24 grit last month) before coating. Want some "tooth" for it to stick to.

Rent a floor buffer, one 24 grit pad is all you should need. Then for the edges use a 5" orbital sander, or a grinder outfiited with as rough as you can find paper to do the edges.


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## BehrRepNY (Jan 27, 2010)

If the concrete isn't failing I would try a concrete bonding primer along with a 2 part epoxy garage floor paint most companies do carry this sw bm and behr


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## NEPS.US (Feb 6, 2008)

BehrRepNY said:


> If the concrete isn't failing I would try a concrete bonding primer along with a 2 part epoxy garage floor paint most companies do carry this sw bm and behr


But the Behr epoxy is garbage.


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## BehrRepNY (Jan 27, 2010)

NEPS.US said:


> But the Behr epoxy is garbage.


It worked great for me in my garage it's all how it's applied but like I said many companies carry so which ever you prefer this should help you


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## Workaholic (Apr 17, 2007)

BehrRepNY said:


> It worked great for me in my garage it's all how it's applied but like I said many companies carry so which ever you prefer this should help you


BehrRep:

Feel free to go to the introduction page and give us a formal intro so we can get to know you and your back ground a little better. A introduction often makes for a much smoother entry into this place.


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## BehrRepNY (Jan 27, 2010)

Workaholic said:


> BehrRep:
> 
> Feel free to go to the introduction page and give us a formal intro so we can get to know you and your back ground a little better. A introduction often makes for a much smoother entry into this place.


Will do thanks for the advice Sean


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## Wolverine (Apr 17, 2007)

I don't even know where to begin. This is almost like being surprised that you bought a Yugo and you're angry that it won't go more than 50 mph. This is so common... 

I'm going to focus on a couple of choices... first... chemistry... second... film thickness. 

Chemisty: 
If you expect quality you have to start with quality. We commercialized the first nanopolymer acrylic (the most advanced acrylic on the market) which is more durable than any acrylic I've ever even heard of. HOWEVER, it's acrylic! If you are looking for a lasting garage floor you should be starting with epoxy. HOWEVER, the only reason to use waterborne or solventborne is because you are not willing to pay for quality. If you want quality you should be looking at 100% solids epoxy for starters. Solvent or Water must evaporate from diluted coatings. When it does you will get shrinkage and a microporous coating that is permeable.

Film Thickness:
How much paint did you use? How many mils thick? It's like buying buletproof armor. If you use the 'cheap stuff' you have to make it thicker. 

I don't have alot of time tonight and the point of this is not to make anyone feel bad. We constantly see facilities that someone painted with cheap stuff... that someone will not pay a heavy price to remove and replace with the stuff they should have used to begin with. 

If you want to get this floor painting and then paint it again in a few years and then paint it again in a few year... grab the alkyd. 

If you are ready to get it done one and do it right:

Prep it right... 
Prime with 100% solids epoxy primer (I recommend and AHC fluoropolymer modified)
Coat with a body coat of 100% solids epoxy
Add Flakes if you want
Topcoat with a 2K high solids ALIPHATIC POLYESTER urethane (85-90% solids)

Another good system would include polyaspartic but it would not be as user friendly. 

Gotta go...


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## foursquare (Jan 3, 2010)

wolverine is right, althouth to much technical talk for me.
go rent a floor scarifier, my b/m store has them. get the moores p40 in a stock color ( you can get the primer if you want [p41]) mix it up for three to five minutes pour it on the floor. spread it out with a squeegee and roll it off. the p40 and p41 will set up in the bucket in 20 minutes so you need to get it on the floor right after mixing. you can have up to 45 -60 minutes to spread and roll, depending on temp, don't use if its too hot it will set up too fast.
i use spiked shoes to walk on the wet floor. and use an anti-slip aggregate because it is self-leveling and when it dries it looks like glass. 

i only get one-half the square footage the can says. figure a gallon per 100 feet, depending on how rought the concrete is. 

if you need help with any of this just let me know.


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## NCPaint1 (Aug 6, 2009)

Workaholic said:


> Yes that was my question, thanks.
> Once you determine that your concrete is ok then the best route but most work and expense would be to shave or grind a layer off of the floor and re etch and then apply a floor epoxy.
> 
> Or as your OP mentioned you could remove any failing paint and smooth the edges and repaint with a garage floor paint.
> Of course if you have other areas that may fail then that could result in making the new coat fail as well.


If you grind, with diamond blades....there is no need to acid wash. The floor will be profiled properly. If you really want a heavy duty finish, use 100% solids epoxy. Most of the floor paints are ok, but not if you will be driving on them, or spilling chemicals, dropping tools...etc. 100% solids is a bit tricky to use, if you decide to go that route, make a new post, and hopefully the epoxy guy will chime in or i'll do my best to walk you through it.


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## Woody (Jan 7, 2010)

scrape, clean again, apply epoxy primer, apply epoxy finish.... drink a beer, and grab the tittys...ra...ra


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## propainterJ (Jan 31, 2011)

I got a guy wants his garage floor done,he says he wants it done with a tough durable finish with color chips in it,he's going to drive on it,it's his workshop,he works on Motorcycles so,it'll take some abuse.

So,diamond grinder,fill cracks and chips,100%solids epoxy primer,100% solids epoxy coating,paint chips,then clear coat?

Pour it on the floor,squeegee,roll it out,this slab is about 4 years old,that probably doesnt matter,still gotta moisture check,this is gonna be fun.


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