Terrazzo has been around for centuries. In its origins Terrazzo was simply marble chips mixed in with colored Portland Cement. The term “Terrazzo” actually is derived the Latin word “terra” which means earth, (I told you it has been around for a while). Typically the Romans used Terrazzo on their outside patios or “terraces”. The colored cement is called the “matrix”, not quite as high-tech as the movies, but as infinitely diverse and interesting as a design element. The matrix is what really brings the beauty of Terrazzo to the forefront.
Let me take a moment here to explain how Terrazzo has traditionally been installed. First, it was poured out, then ground down flat and usually left at a 100-grit finish. At this point a topical Terrazzo sealer was applied, followed by multiple coats of floor wax or finish. This is a time-intensive process, as the floor requires constant buffing and re-waxing to maintain a high-luster shine.
This process has been modernized over time and today, we now have epoxy based Terrazzo,
A bit easier to apply perhaps, but the restoration process is mostly the same, except that densification is not required (and I certainly don’t recommend it).
Since most Terrazzo has already been ground (sometimes as long as 100 years ago), contractors can generally start with 50 or 100 grit resins. In some instances where a floor is very wavy, you may have to start with a high metal diamond instead, but use caution if you drop to lower grit diamond!
It is important to keep in mind that unlike a concrete floor, a Terrazzo surface is generally only 3/8 to 1/2 inch thick. That means if you start to grind with a 50 metal, you could very easily reveal the underlying cement bed and with metal grits, you run the risk of exposing pinhole air pockets that will need to re-grouted with color-matched cement or epoxy maintain the original matrix. These concerns can be avoided if you start off with the resins and work your way in. However, be aware that some surfaces must be started with metals. Frequent floor stripping (using harsh and acidic chemicals) can really damage and “pit” the floor. This scenario surface will most certainly require an initial grind with a low grit metal. This is a pretty tricky craft and I would strongly urge that you consult with a Terrazzo restoration professional before you begin your grinding and restoration until you have sufficient experience to manage these nuances!