One of our larger commercial projects, this is the retail location of a major boot and cowboy apparel retail store located in the Gran Plaza Mall in Ft. Worth, Tx. The existing floor was pretty much a wash; consequently a microfinish concrete overlay was the best bet to refurbish it. This floor was a three-coat process; two thinfinish coats and a microfinish coat followed by an acid stain on top. So just what is thinfinish and microfinish? We'll explain below.
Thinfinish is a concrete overlay material that is the first step in the overlay process. We apply this to create a bond coat that sticks tightly to the floor. This first coat has a very sandy texture to it which results in excellent abrasion resistance. Because this floor was in terrible shape -- cracks running everywhere, pits, and a lot of surface damage -- we had to apply two thinfinish coats on it instead of the one that we normally do. Once the final thinfinish coat dried, we followed it up with another concrete overlay material called a microfinish. Microfinish is a special cement material that has almost no sand in it, so consequently it has a very fine consistency. We trowelled the microfinish on top of the thinfinish, forcing this material into and between the sand grains, which filled the concrete pores up completely and eliminated the sandy feel and created a smooth, easy to maintain surface. We then hand scrape the floor with a razor knife to smooth it out even more.
Sometimes a customer will ask for an even smoother floor. We can do this by including a sanding step, but at an additional cost. But how do you sand concrete? One of the unique properties of a concrete overlay is that it hardens with time. Knowing this we wait a few hours after applying the final microfinish coat and then start sanding it before it begins to really harden. We pass over the entire floor with a large sander that is connected to a vacuum system to keep the dust to a minimum. After sanding, we can then acid or water stain the microfinish. Now, because the surface is very smooth, it doesn't generate as much variegation and mottling during staining process compared to that of our hand scraping process but it's still noticeable. Our next project talks a little more about acid staining, microfinish concrete overlays, and what we do when we find cracks in your floor.