We get a lot of questions from customers who are overwhelmed or misinformed by all the information on the internet about Terrazzo and Concrete restoration. A lot of information on the web is outdated, including the video from an episode of “This Old House”. We hope this information helps answer your questions about the correct way to polish terrazzo and concrete. Please give us a call if you have any questions.
The most common questions we get:
Q. How heavy is your machine?
We use several machines to get the job done; our biggest machine is a 1,450 pound planetary grinder. The smallest machine we use is 200 pounds. That machine is used for edging. The weight of a floor grinder does matter. A heavy machine can help flatten and refine the floor. The more you can flatten and refine the floor, the more durable and higher shine is produced. A marble floor machine or a buffer cannot truly polish a floor. It can produce a shine or what we call a topical polish. But it won’t last without maintenance. You may have also read online about polishing with a buffing pad that has diamonds impregnated in the pad. This will also only produce a sheen that is not durable without maintenance. Topical polishing does have a place in the industry where budget and time is a concern. Are you being quoted a price for grinding and polishing when the contractor is only going to topically polish the floor? Add a sealer and call it a day? We usually consider this cleaning, not polishing. Our system for topical polishing involves using the same type of diamonds we use on our larger machines. It also allows us to deep clean concrete and terrazzo removing a small amount of surface materiel for cleaning, sealing and dust proofing concrete.
Q. Do you run wet or dry?
We run dry 98% of the time, we have a 3 stage, 3 Hepa filter vac system that collects over 99.7% of the dust. We also use a pre-separator during heavy grinding to help keep dust out of the air. The issue with running wet is the mess. I cannot tell you how many jobs I have worked on or seen that a previous company made a mess running wet. Did you know you, the homeowner and the general contractor can be heavily fined if the contractor dumps wet concrete slurry in your yard or near a drain. It is hazardous to the environment as well. We certainly do not want to be the source of any more water quality issues here in Southwest Florida. Sometimes you must run wet because of glue or sealers on the first steps. If we do run wet, we use a system to separate the water from the slurry so it can be disposed of properly. We also use a controlled release of water and never flood the floor causing damage to drywall and wall studs. While there is some debate on what system produces a higher shine, the diamonds for the machines have changed over the years allowing you to run dry and produce an equal or better floor than running wet.
Q. What grit do you start at?
On most Terrazzo floors we start with a 60/70 grit metal bond. (A metal bond diamond is made of metal with synthetic diamonds encased in it). Some floors require the use of a 30-grit metal due to the damage of the Terrazzo, or in the case of concrete how much surface that must be removed to get the proper aggregate exposure the customer is looking for. This is also where the weight of the machine counts. A 60-grit diamond is not the same under a 200/300/400-pound machine as it is under 1450 pounds. In some cases, we can save you time and money by using a heavy machine, starting out at a higher grit.
Q. How many steps do you do?
This is a loaded question. Many contractors will say any number that makes you feel like you’re getting a good deal. Some include cleaning as a step or burnishing/buffing the floor as a step. If we start at a 30-grit metal, our process includes 3 metal bonds, 2 transitional diamond steps (made of a resin, ceramic or copper with synthetic diamonds in it) and 2 to 4 resin (polishing) steps. How many resin steps depend on customers preference and budget. We also do something a lot of contractors skip and that is grout the floor. The grouting process fills in small pin holes that take away from the overall appearance of the floor.
99% of the time an older floor must be ground using a metal bond diamond to start. Burnishing (high speed buffer) the floor at the end does not count as a “step” in my opinion. It may help the shine but is not a grinding step. Ask your contractor exactly what steps they do. Get it in writing and check on the job when possible. I have seen many jobs that customer was told that floor was ground using a certain process and it is obvious that they were lied to.
Q. Do you seal the floor?
Yes, we do, but not in the way you think. During our grinding process we stop, clean the floor and add Densifier (a lithium or potassium silicate) to the floor. This hardens the floor considerably. It helps seal the floor and assists getting that high shine during the polishing process. You cannot truly grind and polish a floor without densifying. With the final step of the job, we add another sealer. We use products from Ameripolish for our Terrazzo floors. We are listed on their website as authorized installers and recently helped them develop a new product just for Terrazzo. They have some of the best products in the industry, we typically use a penetrating sealer that will not scratch, peel or yellow because it penetrates deep into the slab. For concrete, we will use Worx’s + or Ameripolish. They both do a great job and can achieve different looks for the floor.
This brings me to another point. I see a lot of contractors not polishing the floor to a high shine, then using the sealer (Like a polish guard) to get the shine. They will show the customer and it looks great, but when the sealer is gone, so is the shine. There is a lot of sealers “Guards” that shine like crazy and fool you into thinking you got what you paid for. Make sure the floor has a shine because of the grinding process, not the sealer.
Q. What about the edges?
We have a machine that will get right up to the edge. We also use a hand grinder with the proper dust control to polish edges. There has been a contractor in town telling customers that NO ONE can get the edges, and he offers to color or paint a border. This is just pure laziness. Edges take a lot of time and a lot of hard work. It can be one of the most difficult parts of polishing a floor. We do recommend that the baseboards be removed during the process for a cleaner look.
Q. Can all the stains be removed on Terrazzo?
No. But we use several different methods to remove or reduce appearance of stains and have a high success rate of making a floor look great. We will go over the floor with you and point out any areas of concern and explain how we will treat those stains. If a floor is beyond repair due to stains, we can dye the floor. The dye is permanent and colors the floor. Just think of dyeing a shirt.
Q. How long does it take to properly polish a concrete or terrazzo floor?
This is one of the biggest things you should look for. If a contractor tells you that they can grind and polish a house in 2 days, they are not properly grinding your floor. A 1,200 square foot typical house takes 4 to 5 working days to complete. This may not include stain treatment or patch work that can take several days to complete.
Q. Can all concrete/terrazzo be polished?
No. Some concrete and terrazzo is beyond repair. We can pour a new floor over the existing floor in most cases to give you a brand-new floor. We use products from Rapid Set that allow us to start polishing the next day! We can also give you that Terrazzo look using products from Rapid Set for Terrazzo that is beyond repair.