Urethane removal

[workhurts]

I may have asked this before but don't think I got a definitive answer. Since my urethane topcoated epoxy is delaminating (possible application error wrt to humidity) and the probable need to add something with anti-slip, how would one go about removing the urethane without damaging the clear epoxy underneath?

It would be nice to grind or sand the urethane off and not mar the epoxy underneath or at least be able to polish the clear epoxy underneath as an intermediary step.

if I'm too aggressive with the urethane removal and I don't think I need to be because I can pretty much peel it with the side of a coin, I don't want to be doing so much damage underneath that I have to pour more epoxy.

Ultimately I'd go back over everything with more urethane and anti-slip. I should probably experiment but I'd also like to make sure that if I go this route, I remove all the urethane. Since it's clear urethane it's sometimes hard to tell what's left and whats not left. I don't want to re-pour urethane over bad urethane.

Its behaved as sacrificial layer over the last couple of years, and looks decent enough which is why I haven't bothered with it but if I'm adding another layer with anti-slip I should fix it.

 

[benwah]

Go ahead and sand it down. You really want to mechanically abrade the epoxy anyways before coating with polyurethane since you are out of your re-coat window..

I am assuming your urethane is clear also? When you apply, it will hide the sanding marks. Be sure to give the floor a good alcohol wipe before applying this stuff. Make sure all dust and debris is cleaned up.

 

[Jim B]

In my limited experience with this I've found that if you scratch the epoxy it really shows when you apply the urethane. Looks like a$$ if that happens so be careful.

 

[benwah]

Jim,
What products are you using, specifically? If you do not mechanically abrade that floor before applying a polyurethane topcoat, there is a very good chance you will be in the same predicament you're in now. Since you are out side of your chemical re-coat window, that about the only option you have. Now don't go sanding it to hell with 60 grit sandpaper. Personally, I've found 200 grit or sanding screen to do the job works fine. All you want to do is promote adhesion for the polyurethane to adhere to.. Or "degloss" if you will. If you try to roll that on a slick epoxy floor, it will probably peel up.

 

[LegacyIndustrial]

He may need 80-100 to get into the urethane. 200 probably wont do much.


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[benwah]

That's true, and without seeing it, it is hard to just pick the correct grit and say OK. I stated 200 because it sounds like the urethane is peeling up anyway, but yes Legacy is right, you may need a tougher grit. Mess around and see what works best.

 

[workhurts]

Thanks for the input.

At what grit level would re-applying urethane not look horrible?

I was going to use the same urethane I had used before from originalcolorchips which was the HPU747 VOC but I could use just about anything else although they do owe me some new urethane.

I'd sand, wash, dry, and then use mek or something to open up and soften the epoxy and then urethane if that makes sense.

 

[benwah]

Not sure where you got the idea to soak your epoxy floor with MEK to soften it? I wouldn't recommend doing that.

 

[LegacyIndustrial]

Solvent can be used to clean off any dust. Fine dust can hide in the scratches made during preparation. Denatured alcohol is great as it dries fast and has a low smell as compared to Xylol or MEK. As Benwah stated, don't try to soften, you want it hard and scuffed.

 

[workhurts]

sorry, it's been a while. I meant xylol not mek and perhaps soften was also a poor choice of words.

So, how aggressive of a grit will urethane hide? 60, 100, 200 ..

Now that I'm thinking about this again, would it make more sense to go aggressive to make sure I get all the old urethane off, coat with another clear and then urethane?

And the flip side, is there any way to get the urethane off and still make the clear under it look good? Like polish with 400 or 600 or 800 or 1000 or whatever grit?

 

[LegacyIndustrial]

100 grit and you should be ok for a recoat. Do a test in the corner.

60 will be tough to cover.


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