Bobby the Terrazzo Guy

This is Bobby the (self-described) Terrazzo Guy, his name is actually Wentworth Thomas, rather distinguished sounding, eh? Anyway, Bobby is, how should I describe this, finish-grinding the white cement and white sand concrete mix, which is the top coat of our finished floor. About 1/2 - 3/4" thick or so, more recenetly troweled on top of the rough slab we poured months ago.
Bobby is shown here, using his small rotary machine with diamond blades, I think he was using 80 grit at first, finishing with a 120 grit metal blade.
The machine itself is called a planetary polisher, that is, the round diamond-embedded grinding disks (five or seven) are also spinning, in an opposite direction than the main blade, to ensure a smooth surface, free of grinder marks. Get it, the small planets (grinding disks), rotate around the main planetary body? The master bedroom floor, shown here, is getting ground down and the slurry, or spoils of the grind, are mopped and vacuumed up with a wet vacuum system. Creating zero dust, zippo, none, he left the floor smooth and wet and clean!!
The next step, after his water has evaporated, and the floor is dry again, I begin by applying a first coat of stain with an insect sprayer, the kind you pump up by hand. I leave the stain sit on top of the cement and let it doing it's work, burning it's color into the concrete's DNA. There is no going back and there is no certainty to the color of the final product, it will be what ever it will be, end of story. Isn't it grand - no control at all - absolutely none.