As I said in post 29, a friend and I went over the whole floor with the buffer and black pads and it looked real good. I should have put on the u140 at that point. But, I coated the whole floor with a colloidal silica densifier and my problems began. In retrospect, I may have been ok if I had let it sit for an hour and rinsed the densifier off, but, apparently my concrete was already fairly dense from the power trowel. Anyway, it didn't soak in much and left a nasty film. At first I thought I was ok because the film was transparent. But if you rubbed your hand across it, it would leave white residue on your hand. Worst of all, if you scraped it, it was fairly deep. So back to the drawing board. I tried to buff it off with the black pad, but that didn't quite get it all off. I then rented the 25 grit diamond plate for the buffer and ground my largest garage. I went both directions and it took me about an hour per 100 sq ft (1,200sqft.) not wanting to spend another 15 hrs grinding I experimented with some muriatic acid. With the proper mix and soak time it seemed to take the garbage off. So after the grinding, etching and tons of sludge later, I went back over the whole thing, all 2,750 sqft with black pads and made some more sludge.
Figuring the part that I had treated with acid was maybe not as absorbent as the diamond ground part, I figured I might prime that section. And the cussing ensued. I was sure I was in the process of the next big mistake. For some reason that I don't understand, rather than making it easier to wipe on with the microfiber pad, adding extra water to the mix made it feel like I was applying elmer's glue. But, after much effort and a contorted mop, I got it covered. The next day I decided to do the 18" roller thing. That went fairly well. I would definitely advise using the roller for the first coat. The next day I put the 2nd coat on with the microfiber mop. That went on nice and fast. A couple things I learned, Ace garden sprayers work much better than Home Depot's. The nozzle design doesn't clog. If you have a large floor, buy extra rollers. My first one stopped working after about 1,600 sqft. Oh and don't try to save mop pads or rollers, this stuff is not water soluble, it is waterborne polyurethane and is sticky as heck. Days later I still have it on my fingers. The stuff sticks!
As for coverage, I used one gal for the primer (makes 2 gal) and that did 1,450 sqft. I didn't use all the primer so I got real close to the 800 sqft/ gal. That left me with 7 gallons. I did 2 coats on 2,750 sqft and had a half gal or more left over. So I averaged about 850 sqft/gal. I have been doing this with the temperature at the very bottom of the recommended temperature, just over 50 deg. Seems to take about 3 days to harden up good at these temps. I could easily walk on it the next day.