So, I have what are hairline cracks and some pock marks. The two hairline cracks are pretty small but extend 3/4s the length of the garage. I have two expansion joints or at least what might be expansion joints but they aren't huge. It's like they put expansion joints in and then covered them with concrete. They are hairline straight cracks that go from the garage doors to the opposite wall (exactly where an expansion joint would be).
I was going to fill the pock marks (literally about a dozen very small ones in a single 5' x 5' area).
From my reading, it seems that the cracks might show up through the epoxy but what I'm trying to determine is whether all cracks show up or just large ones? I don't mind patching them up if it's needed.
As for the pock marks, wouldn't the epoxy just fill in? Same for the hairline cracks for that matter? Seems like the cracks were more pronounced after the grinding.
Any issues with the rustoleum 2 part patch? I don't need to buy a gallon from some of the vendors since I don't have much to patch.
Hi Workhurts, go back and read many posts on grinding prep the last few months. These things are all covered here already, but as a summary, the epoxy will reveal *any* defect below it. If there is a 1/8" hole, it will show up after epoxy. LIttle cracks will show up after epoxy. The reason a self leveling epoxy won't really self level is that it gets rolled and backrolled. The epoxy is soo sticky that it will "pull" out some of the epoxy that was in each hole when it rolls past with the roller. Backrolling helps but then pulls some the other way. You end up without being able to fill each little hole. The larger ones will still be holes after the self leveling epoxy coat is on the floor. Now each application of epoxy reduces the magnitude of this, so a full primer would help, but still not completely fill in each hole. I would fill the cracks and all larger size holes as prep before a primer or basecoat for these reasons.
Larger cracks or holes can be filled in with a mix of about 4 parts white silica sand to 1 part of the rustoleum 100% solids epoxy patch to stretch it. First, clean out any crack with a little dremel bit to remove any soft cement material (don't go crazy with that but chase the crack lightly). Then vacuum out, fill in, and overfill it slightly. Come back 24 hours later. Grind off lightly and fast. The surface should be perfectly flat with the surrounding floor.
There might be a few areas with some pullout where you need a 2nd coat same way. To make it perfect where needed, you could follow up with a very light skim coat of just pure epoxy patch without sand. I would just use a little tiny hand squeegee to spread that or a small spreader blade. You can pre-heat the epoxy patch with a bright halogen work light or heat gun for a couple minutes before mixing the two parts. This will lower the viscosity so it is easier to spread thin. BUT, it will also then become hard much faster, so do a small amount at a time and mix as many batches as you need but pre-heat to make it easier. You could also thin with chemicals but then your resulting epoxy won't be as strong so a tradeoff there. Treat the holes the same way as above.
If you wait over 24 hours after a final skim coat or "partial primer" coat before you put on your basecoat, you must rough up that coat a little for your basecoat or real primer coat to stick. Use an orbital sander or sander wheel on a grinder to do this to rough it up a little - 60 grit or 80 grit or so. Using a primer coat on the whole floor will help to fill in all those little holes or defects so they don't show up in the basecoat as much, as well as reveal any fisheye problems or air bubble problems before you get them in the basecoat. In a primer coat, you can then fix those things before the basecoat and have a perfect basecoat. These are some reasons people use a primer on the whole floor first. But at least fill in the cracks or larger holes or rougher areas as above to have a better basecoat. PM me with any questions and I will try to help - Paul
