Epoxy Prep

[pimp-boy]

Hi, I recently completed building my garage from scratch. I'm planning to epoxy the floor. During the construction, **** (sheetrock, people dropping KFC, paint), got on the floor. I was able to powerwash most of the **** off, but the paint (Behr primer & paint) got on the floor from the painters not covering the floor. So, basically, there is paint overspray on the floor. I have a 3000 PSI washer and tried spraying it off the concrete, but it won't come off.

If I just acid etch the concrete with Muriatic Acid (since I have to do it anyways), would this be ok? Or would I have to remove the paint overspray first? I want to put the epoxy down once.

Thanks!!

 

[NextCoatings]

I'm a bit anit acid to begin with simply because it weakens the surface of concrete and is a major casue of a lot floor failures. It's my opinion that the best surface for any floor coating is a clean well scored floor. You should be able to rent a satellite grinder locally for a reasonable price. Shouldn't take more than a couple of hours to prep the floor. Time well spent...you won't regret it. Not to mention, you can kill two birds with one stone (clean and prep your floor)

With new concrete and acid etching, I would check with the concrete contractor and ask about the use of acid on your new floor.

 

[munkey]

If you're just talking about some well adhered spray mist-like dots here and there, I'm willing to bet they don't matter that much. If you're talking about gobs of paint I'd get it off.

Is the concrete porous? If not, you're probably going to want to grind it anyways so just rent the equipment and do it all in one shot. If the concrete is otherwise ready for epoxy and just has some paint splatter I'm sure you can figure out a way to get it up (althought acid probably WON'T do it.) Depending on how much area you're talking about, you could consider a floor scraper, chemical stripper, or even a wire brush on a drill if its only a few spots here and there.

I bet some of the pros here could give you better advice with a picture or two, although my bet is they're all going to tell you "just grind it." That's certainly the foolproof plan if you really, really want your coating to last.

 

[pimp-boy]

Since the paint and primer were sprayed on, there are areas of mist and areas where it is a little thicker. Just reading both your comments, I'll probably just rent a machine and score the surface. Scoring this surface should remove the paint on the surface I presume. The concrete should be porous as nothing was done to it after it was poured. Basically virgin concrete.

If you're just talking about some well adhered spray mist-like dots here and there, I'm willing to bet they don't matter that much. If you're talking about gobs of paint I'd get it off.

Is the concrete porous? If not, you're probably going to want to grind it anyways so just rent the equipment and do it all in one shot. If the concrete is otherwise ready for epoxy and just has some paint splatter I'm sure you can figure out a way to get it up (althought acid probably WON'T do it.) Depending on how much area you're talking about, you could consider a floor scraper, chemical stripper, or even a wire brush on a drill if its only a few spots here and there.

I bet some of the pros here could give you better advice with a picture or two, although my bet is they're all going to tell you "just grind it." That's certainly the foolproof plan if you really, really want your coating to last.

 

[munkey]

Scoring this surface should remove the paint on the surface I presume.

Yes, a concrete grinder will turn the top layer of concrete (and anything on it) into dust. Beware that the amounts of dust can be huge and disgusting, so if you can hook your grinder up to a shop vac or something you'll make the work a lot easier. You should probably wear a respirator either way... if you haven't done it before, it's a lot messier of a job than it sounds. There are also ways to wet grind it but I don't know much about that and whether that is an option will depend on the equipment you use.

The concrete should be porous as nothing was done to it after it was poured. Basically virgin concrete.

Virgin concrete is good, but whether the top layer is porous or not is still a function of whether it was smooth troweled after it was poured. (Somebody can correct me if I'm wrong about this).

From what I've read, what you want to end up with is a sort of rough surface that quickly absorbs a little bit of water instead of causing it to bead. (You can test this easily enough.) It probably won't end up being SUPER rough but once you get started you should easily be able to see the difference.