The Truth in Terrazzo and Concrete Polishing

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   A lot of information on  the web is outdated, including the video from an episode of “This Old House”.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 question about the correct way to polish terrazzo and concrete.  Please give us a call if you 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 765 pound planetary grinder. We can add another 120 pounds when needed. 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 can not truly polish a floor. It can produce a shine or what we call a topical polish.  But it wont last without maintenance. You may have also read online about polishing with a buffing pad that has diamonds impregnated in the pad.  This is will also only produce a sheen that is not durable with out 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 a 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 you run wet or dry
We run dry 98% of the time,  We have a 3 stage, 3 hepa filter vac systems that collects over 99.7% of the dust. We also use a pre-seperator during heavy grinding.  The issue with running wet is the mess.  I can not 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 home owner 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 Florida.  Sometimes you have to run wet because of glue or sealers on the first steps.  If we do run yet, 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 dry wall 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 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 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 800 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 your getting a good deal.  Some include a 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 (made of ceramic/copper with synthetic diamonds in it)  steps and 2 to 4 resin (polishing) steps.  How many resin steps depend on customers preference and budget.  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 where 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 silicate) to the floor.  This hardens the floor considerably. It helps seal the floor and assist getting that high shine during the polishing process.  You can not truly grind and polish a floor with out densifying. With the final step of the job, we add another sealer. We use products from Ameripolish.  We are listed on their website as an authorized installer and recently help 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 in to the slab.  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 Prosoco Polish Guard)  to get the shine. They will show the customer and looks great, but when the sealer is gone, so is the shine.  There is a lot sealers “Stain Guards” that shine like crazy and fool you into thinking you got what you paid for. Make sure the floor has a high sine 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 lot of hard work. It can be one of the most difficult parts of polishing of 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/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 concerns 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 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 1200 square foot typical house takes 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.