Laying epoxy over epoxy - prep questions

[dkhoe]

Has anyone laid epoxy over a previously epoxied floor? What preparation steps would you guys recommend? Just light sanding/scuffing or should I try to remove the old coating completely?

The floor was coated about 5 yrs ago, and for the most part it's holding up pretty well. Some small isolated areas have peeled (less than 1 sq ft each), and there are also some blemishes such as drag marks and spatter spots from welding. I would like to achieve a uniform "new floor" look by coating the entire floor with new epoxy.

I've been told that the old epoxy was General Polymers 3744 (top coat) in a gloss finish. According to the data sheet I found online, it's a high solids "CR" epoxy (not sure what the CR stands for).

Any help appreciated!

David
Santa Ana, CA

 

[tncatadjuster]

Chemical Resistant. Sand it like crazy and go for it. The areas with no epoxy will need to be feathered in, and a little extra 100% solids epoxy over them. I like to use crack filler to ease the transition. Use the paste to fill the drag marks if they are large.

 

[thegarageguy]

the failed are should be diamond grinded, the rest cab be sanded with a 36 to 60 grit sand paper, basically knock off the shine, then use acetone or denatured alcohol to solvent wipe, then recoat.

 

[Edger]

I would grind it all back because sanding never worked for me, the abrasive was not hard enough, and if you have some areas peeling then the entire floor was not prepped properly, also you will get a smooth, uniform finish from a complete diamond grind.

 

[rugerlady]

I agree with the garageguy. This would also be my recommendation. The bare spots will need to be diamond ground. Also, you may want to consider diamond grinding the entire floor, if the initial coating is failing in some areas, it may continue to fail in other areas as well. If that occurs, your new coating will peel up as well.

 

[dkhoe]

Thank you for all your suggestions.... much appreciated!

Since the epoxy has held up for 5 yrs except for the isolated areas, I was hoping that I would NOT need to grind it all off. Yes I know, it would be at my risk of future problems.

What I didn't mention in my first post is that this floor is not a garage but an industrial space (about 1800 sq ft) which had been previously restored with a layer of self-leveling cement-based material (anywhere from 1/8" to 1/2" thick). So the entire floor was entirely level and smooth prior to the epoxy coating. If I start grinding the epoxy aggressively, I'm afraid I could gouge or dig into the (possibly softer) cement material underneath and make the appearance worse!

I'm leaning towards the suggestions of diamond grinding just those isolated areas where the peeling occurred and level them as best as I can, then roughly sand the rest. I'll post updates when the work starts.

David

 

[pd59]

Thank you for all your suggestions.... much appreciated!

Since the epoxy has held up for 5 yrs except for the isolated areas, I was hoping that I would NOT need to grind it all off. Yes I know, it would be at my risk of future problems.

What I didn't mention in my first post is that this floor is not a garage but an industrial space (about 1800 sq ft) which had been previously restored with a layer of self-leveling cement-based material (anywhere from 1/8" to 1/2" thick). So the entire floor was entirely level and smooth prior to the epoxy coating. If I start grinding the epoxy aggressively, I'm afraid I could gouge or dig into the (possibly softer) cement material underneath and make the appearance worse!

I'm leaning towards the suggestions of diamond grinding just those isolated areas where the peeling occurred and level them as best as I can, then roughly sand the rest. I'll post updates when the work starts.

David

I agree with all of the above advice, but I would like to add that when I go over old epoxy, I usually like to mop the floor with some denatured alcohol after sanding to make sure the floor is really clean before re-coating. And really make sure there are no other failed areas on the floor.