At the end of my last post in this series, work had begun on polishing the concrete floor. This process involves numerous steps. First, the concrete must be “sanded down” (that is not the technical term) until the surface is very smooth. This is done with diamond cutting discs that, like sandpaper, come in various degrees of coarseness. This process exposes the aggregate (little rocks) in the concrete, which were pushed down into the slab when the guys who pour it do their magic with the long boards to smooth it out and remove air holes from the surface layers. Personally, I love the look of the exposed aggregate – it gives it that look of raw, natural materials that I am going for in this home.
Next, a “densifying agent” was applied to the concrete. This serves to harden the concrete and make it less permeable so that it won’t stain easily. We were told, for example, that if you spill a cup of coffee on the floor and wipe it up within a few minutes there will be no stain, but if you left it overnight it would stain. After that, the concrete was polished using steadily finer surfaces until we achieved the level of reflectiveness we wanted. I did not want something too shiny, so we had him stop at 800-grit. The next level up is 1500-grit which would have been more like a showroom.
Before I show photos of the finished product, I wanted to say that while researching this topic it was really difficult to get an idea of what colour, exactly, the floor would be when it was done. This is for two reasons: first, the materials used in concrete vary slightly depending on what part of the world you are in and where the sand and other ingredients are sourced. Second, taking photos of this stuff is really hard – at least for those of us who are not professional photographers! The light can change the look of the floor in a photo dramatically, even though when you are standing in the house the floor is a consistent finish. This is illustrated in the series of photos below.
I want to give a shout-out to Rami and Oscar of Concrete Evolution, who did our floors. They worked tirelessly to give us what we wanted, and were a real pleasure to work with. Rami explained every step of the process and helped us decide whether or not to go with added finishes like dyes or colour overlays (we decided not to because we wanted a more natural look).