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How To Get a Lasting Shiny Finish Using Terrazzo Sealer | All About Sealing Terrazzo
In this post, we cover simple ways to get that lasting shiny finish and keep your terrazzo looking clean and beautiful for longer.
Table Of Contents
- What Is Terrazzo Floor Made Of?
- What Happens When You Don’t Seal Your Terrazzo Floor?
- What Are The Different Types Of Terrazzo Sealers?
- Which Terrazzo Sealer Is Right For Your Project?
- Common Problems With Common Terrazzo Sealers
- How To Seal Terrazzo | Preparation & Application
- What Are The Best Practices To Keep Terrazzo Floors Clean?
- Sealer Incompatibility Issues
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Terrazzo is a hard floor that can withstand high traffic for decades and is as durable as it is stylish. But Terrazzo is not exempt from the typical wear and tear that can stain and scuff the surface, so it is best to apply a specially designed sealer to prolong the life of your floor.
Let us first explain what terrazzo is made of in order to better understand what products work best to protect it.
What Is Terrazzo Floor Made Of?
This aesthetically pleasing floor is actually split into two types: cement terrazzo and epoxy terrazzo. Essentially, terrazzo is made up of a mixture of either cement or colored epoxy, chips of stones like marble, quartz, and granite, and even shards of seashells and glass.
This blend of aggregates is what gives Terrazzo it’s signature colorful appearance and aesthetic. This wet mixture is then spread out smooth on a floor, and ground to expose the aggregate as well as polish to increase the shine.
Older properties tend to have older floors; older terrazzo tends to be cement based. They would build the floors first, make the terrazzo, and construct the building around them.
Nowadays, the building is constructed first and then epoxy terrazzo is used. We see terrazzo in all kinds of buildings: airports, hospitals, schools, supermarkets, and stylish residential homes. It’s a very tough, very durable floor. And although it’s an expensive floor, it is still very popular here in the US.
What Happens When You Don’t Seal Your Terrazzo Floor?
So if you don’t seal terrazzo, you leave it extra vulnerable to staining and wear.
Because cement terrazzo, in particular, is so porous, not using a sealer greatly reduces its durability and therefore its lifespan.
And while epoxy terrazzo is not absorbent, it can still be easily scratched or scuffed. Having a sealer on the surface will help protect the terrazzo and make it much easier to maintain.
So if you want easier cleaning and maintenance, as well as longer serviceability of your terrazzo floor as a whole, it’s best to use a proper sealer.
What Kind Of Sealer Does Which Kind Of Terrazzo Need?
The type of terrazzo floor will, in fact, determine the type of sealer you should use.
Cement terrazzo floors are made with a slurry of cement, which means they are more porous and more absorbent. For these, you can use both topical sealers and penetrating sealers.
Epoxy terrazzo is made from epoxy resin, which is a tough polymer that is not absorbent. Only topical sealers will work on terrazzo made of epoxy.
What Are The Different Types of Terrazzo Sealers?
There are a few types of sealers, each with their own characteristics: penetrating or impregnating, topical, or polyaspartic.
Penetrating sealers are used to soak into porous cement terrazzo, but not change the visual appearance or risk increased slipperiness. Penetrating sealers cannot be used on epoxy because it is simply not absorbent.
Topical sealers form a film over the top of a dense surface which is an excellent way to change the look or finish of terrazzo, but it can prove slippery when wet. This can be remedied by mixing in anti-slip aggregate with your topical sealer before applying.
Polyaspartic is a newer technology type of sealer, but really, we classify it more as a coating than a sealer because it goes on a little thicker (6-10 mls) than the way a standard sealer would (3 mls or less). This extra viscosity is due to the larger concentration of active solids (85% or more) as opposed to typical sealers (12% – 50% depending on quality). It has the toughness of an epoxy, but has the UV resistance, non yellowing characteristics, of polyurethane. Also, it sets much faster; it typically dries in 15 to 20 minutes.
Polyaspartics have a lot of advantages when you are doing installations for quick turnaround. They are more expensive. Our polyaspartic coating is called CoverShield P650 FS (for fast-set), and that is water-clear. That can be used in both interior and exterior settings as a topical coating over epoxy terrazzo. It can also be used to protect cement terrazzo. Polyaspartic sealers give terrazzo more visual depth, and more scratch resistance.
Which Terrazzo Sealer Is Right For Your Project?
The right sealer for your project depends on the type and size of the project, as well as any constraints like odor exposure, dry time or return to service time. This would apply to high traffic, enclosed places like hospitals and schools, where exposure to chemical odors is especially hazardous. To avoid this, use a water based sealer instead of a solvent based (chemical based).
Polyaspartic coatings actually set and dry very fast, so they will usually be solvent based to allow more crucial working time.
Cement terrazzo has some porosity, so penetrating sealers can be used if you don’t want to change the color or sheen to make it more shiny, for example.
Polyurethane sealers give great stain and wear resistance. Our Strong Seal Plus, which is a two-part sealer. Our one part sealer, the CoverSeal AC450, is acrylic-based and also very stain resistant, just not as durable as the StrongSeal Plus. But it is faster drying and easier to apply.
The AC450 is great for restaurants, food courts, etc. that would depend on quick turnaround or drying time. For higher traffic areas, like warehouses, they might prefer the StrongSeal Plus for its higher durability.
Those are our two main products that we would recommend for sealing terrazzo floors. Both of those can be used on cement based or on epoxy based terrazzo.
For penetrating sealer options, then we would be recommending the CoverSeal Premium for the oil and stain resistance properties that it brings.
All those products are water based and so much easier to use. There is very little odor and no constraints as far as using them indoors.
How To Tell If Your Terrazzo Has Already Been Sealed?
Remember that epoxy terrazzo is not porous, so the only visible indicator of a previous sealer would be any lifting or peeling of film on the surface. This visual test also works on concrete, as you might see some shiny film flaking off. However, that is not always the case.
A simple and effective way to check if your cement terrazzo floor is already sealed or not, is to test for porosity.
A simple water test will do: just take a small amount of water and splash it onto the surface and leave it there for about five minutes. Then brush or mop the water to one side, and observe if there’s any darkening of the surface, indicating any absorption of the water.
If you don’t see any darkening, or if the water beads up on the surface, then that’s telling you that it’s been sealed either with a topical or a penetrating sealer.
And then lastly, if it’s a cement floor, you can apply a slightly acidic solution, even a splash of vinegar, to a discrete area.
Once you do, look to see if there’s any fizz on the dampened surface. That would give you an idea of whether there’s a sealer on there. There won’t be any fizz if there’s a sealer present. If it’s not sealed, then that acidic solution will react with the cement and produce a bit of fizz.
So there are three ways you can determine if your terrazzo has been previously sealed or not.
Common Problems With Common Terrazzo Sealers
The kind of terrazzo sealers that you can find in a big box shop like your local home improvement store, tend to be lower quality products.
The way to lower the cost of a sealer is to reduce the active solids content in each batch, which lowers the production cost. This allows the manufacturer to sell the product at a lower price while still making a profit.
Unfortunately, that lower solids content makes those standardized sealers far less durable, and less UV and stain resistant. It also means you will have to reapply the product more frequently to maintain some form of protection for your terrazzo floor.
We also see standardized acrylic sealers that are softer. They might have a higher solid content (near 20%) but they use softer acrylics in general. These start to yellow and pick up dirt easier and break down faster with cleaning chemicals. So while a standardized acrylic sealer may polish up nicer, and give a higher shine, you will lose more durability in the long run.
We often get complaints of water whitening. This appears, for example, after a cleaning bucket, mop, or even a damp cloth has been left on the floor for a few hours, so when it finally gets removed, there’s a white ring, or mark, left on the surface that sometimes won’t disappear no matter what you do.
Lastly, because of the low content of active solids, these local-bought sealers have a higher concentration of the caring agent, which is usually solvent based. Maybe 80% of that gallon of sealer is actually solvent.
Solvents are much more hazardous to use, as they are very odorous and flammable, and not at all eco-friendly.
These are the sort of problems you get with these standardized sealers made from lower-quality resins.
We formulate with much higher solids contents and with much more durable polymers. Our two-part polyurethanes, for example, are two to three times the amount of solids that you would find in a typical big box store. We don’t use solvents either, we use mainly water-based products, to maintain health standards for our staff and our clients.
How To Seal Terrazzo | Preparation & Application
So the application of a good sealer actually depends on the available surface texture of the floor. This will allow for good adhesion of the sealer.
First, you’ll want to take care of any stains, dirt, oil, or grease – especially common to food prep areas. Microbial cleaners are best for safely and effectively deep-cleaning the terrazzo floor. The microscopic organisms in this type of cleaner actually eat away all contaminants and leave no residue behind!
Our CoverClean FG (which stands for food grade) works particularly well on porous surfaces, like cement terrazzo. And for epoxy terrazzo that’s not absorbent, we have our Emerald Floor Maintainer.
Next, we have to address any previous sealer. Any existing sealer will interfere with the bond of a new sealer, regardless of the type of terrazzo you’re working with, so it must be removed. Typically, we’d be using our FloorStrip HP, which is mopped or sprayed onto the floor with a low pressure sprayer. Give the chemical stripper a bit of agitation with a deck brush, or even a floor scrubbing machine to remove that sealer. Then vacuum or mop up any residue and let it air dry. This is the same kind of good preparation that you would use on a concrete floor.
Another option for prep is to actually grind the floor, or lightly sand it to remove any sealer and just clean up the dust. It’s an effective preparation method to avoid using any stripping chemicals or water, whether you’re working on a cement or epoxy-based terrazzo floor. Just lightly sanding with a floor-buffing machine and a sand screen.
We always recommend that you thoroughly clean the terrazzo surface first and then grind, so you’re not driving any of that oil or grease deeper into the floor.
As far as the application is concerned, both our StrongSeal and our CoverSeal AC450 are topical sealers and can be easily applied with a flat mop or ⅜” nap roller, or with a pump up sprayer and then spread out with a flat mop. (But we always recommend the roller as the best tool for even, methodical application.)
Remember that the StrongSeal Plus is a two-part polyurethane that must be mixed first according to the instructions on the packaging. We generally recommend only one or two coats, and depending on the porosity of the terrazzo surface, you can get anywhere from 300 sq ft to 800+ sq ft per gallon.
The AC450 takes two – three thin coats, and with this product you can get about 1,500 – 2,000 sq ft of coverage.
Especially useful on cement based terrazzo is our CoverSeal Premium penetrating sealer, which can also be applied with a roller, low pressure pump up sprayer, or even a lambswool applicator. This product usually only needs one coat, and will give about 175 to 200 sq ft per gallon.
Drying Times For Terrazzo Sealer
The drying time of a sealer greatly depends on the environmental conditions – cold makes typically makes the chemical reactions of sealers slower, and therefore makes them take longer to dry. However, of course, we don’t want to be applying sealer on anything over 100 degrees Fahrenheit (like on a stylish terrazzo patio) as the sealer will burn before it can adhere.
It takes about 12 hours for the StrongSeal Plus to dry, and it takes only two to three hours for the AC450 to dry. Remember, acrylic is a faster-drying polymer. We recommend waiting at least two hours and until the surface is tack-free before walking over it, and six to 8 hours before permitting any regular, heavy foot traffic. Wait at least 24 hours before permitting any vehicular traffic, to avoid the hot tires picking up the sealer or leaving permanent tracks.
A penetrating sealer dries at a much different rate. Most of the CoverSeal Premium penetrating sealer should be absorbed into the surface within 15 minutes, and any access should be wiped off after that time. Note: if it’s completely absorbed much quicker than that, then we recommend a second coat applied in the same manner, with the excess wiped off after. Wait around two hours to walk over a penetrating sealer, and six hours for permitting any serious foot traffic. It’s best to way 24 hours minimum as a rule of thumb before permitting vehicular traffic.
How Long Does A Terrazzo Sealer Last?
How long a terrazzo sealer lasts depends on where it’s being used. For example, the sealer on the floor of a food court is not going to hold up as well as the seal on a residential floor.
In general terms, a terrazzo sealer will last about a year and a half to two years in a high traffic, likely commetial, area, and about three to five years in a smaller or more residential area with high foot traffic.
What Are The Best Practices To Keep Terrazzo Floors Clean?
It’s important to keep dust and dirt and sand off the floor as much as possible. Keep that down to a minimum is tip number one for keeping a terrazzo floor properly clean.
This requires routine dust mopping and sweeping. An extremely convenient method is to use floor matts inside each entry way of a home or facility to trap loose particles.
We also recommend avoiding using any harsh chemicals, as they shouldn’t be necessary but can actually damage the integrity of the sealer itself.
That’s a good practice to keep any floor clean, regardless of the sealer. But now the floor is sealed, it is much more stain resistant, much more repellent, and therefore much easier to keep clean. So use only neutral pH type cleaners, and nothing too acidic or too alkaline, like bleach, ammonia, and vinegar.
Instead, use our Emerald Floor Maintainer. That’s an excellent neutral cleaner that contains microbial enzymes that actually break down the contaminant particles without leaving any residue at all. It’s concentrated in its packaging, which makes diluting it for use economical too. After you’ve used our Emerald cleaner, you go over it again with a damp mop and then just let it air dry.
If you need to use a heavier degreaser, then we have our SurfaceClean, which is best for large spaces like warehouse floors. But you generally don’t see that concern with terrazzo flooring.
Usually, you’re dealing with terrazzo in social places and food prep areas, so the Emerald Floor Maintainer would be great for everyday cleaning and the CoverClean FG is great for any surface touching food.
You can use home remedies or diy cleaners made from natural products, just be careful about the concentrations of your ingredients; make sure again that nothing’s too acidic or alkaline. They can dull the finish or even burn the sealer itself if they are too acidic or concentrated (like citric acid and vinegar).
A quickly deteriorating sealer means replacement costs and more labor.
Also, we want to avoid leaving any residue from things like baking soda and hydrogen peroxide. This residue can dull the finish of the terrazzo as well, besides simply creating more work – which we were trying to avoid by using a sealer in the first place!
That’s why sometimes it’s better to use a cleaning product that’s already formulated properly. That way you’re not subjecting your floor or your environment to potential chemical hazards; mixing concoctions can mistakenly produce ammonium gas, which is very toxic.
We also have our SurfaceTreat, which is a unique cleaner that does wonder on terrazzo floors, especially after using our AC450 or our VS1 to seal. This SurfaceTreat contains a polishing compound, meaning that after you clean and cleanse with it, you can come back and polish the surface to increase the shine.
The SurfaceTreat product is more of a commercial cleaner that a contractor could use in combination with the appropriate buffing and burnishing floor equipment. And it is a great option for janitorial or other cleaning companies to use in order to maintain terrazzo floors.
It is designed to clean and cleanse the sealer that you’ve put on your terrazzo floor so you don’t have to come back and have to strip and wax – or even grind off – an existing sealer. You can just clean and cleanse the surface with our SurfaceTreat up to four layers deep over the floor without having to replenish the existing sealer. It serves well to increase the longevity of your floor and its shine without having to use more sealer.
How To Spot Repair Terrazzo:
Repairing a terrazzo floor with a large scratch in the sealer is similar to repairing that in concrete.
The affected area should be scrubbed and lightly sanded first, taking care to remove the dust afterwards. And then reapply a little of the same sealer. The faster drying products, like the AC450, make repairing easier, but they’re not as durable as something like the StrongSeal Plus.
That’s just the trade off of the AC450: it will be easier to repair and it is still a tough sealer that will last longer than most of those big-box store sealers but it’s technically not as durable as the StrongSeal Plus.
The StrongSeal Plus will require more sanding than scrubbing in order to recoat it – but you would do that less frequently.
A Note on Sealer Compatibility Issues:
You can technically use a different sealer to repair your terrazzo floor than the one currently on the surface, but you have to be careful and make sure the sealers are actually compatible. So if you’ve got a solvent based sealer and you plan to go over it with a water based sealer, you could run into serious problems.
If the sealer is very old it may be possible to go over it, but we would recommend that you strip that and start fresh instead. If you’re dealing with an existing water based sealer, then you’ll want to go over it with another water based like our AC450.
If the sealer you want to use to recoat is not compatible with the sealer already on the floor, they will pull apart and separate. You’re going to see that it’s almost like oil on water; the sealers will pull apart from each other. That’s indicating you should surely strip it off and use the right type of sealer.
Using a different sealer also runs the risk of altering the appearance of the floor as a whole. You will likely have a different sheen over the repaired area as opposed to the rest of the surface. So, if you’re going to go over an area to repair it, it’s better to do the whole floor than try and do a spot repair with two different topical sealers.
When it comes to penetrating sealers, again, you must be mindful of the incompatibility. If there’s a penetrating sealer on the floor, its very difficult to go over that with a topical sealer, particularly a water based one. That is because the whole function of the penetrating sealer is to repel moisture and water. So the water based sealer will not lay very well at all.
Be very careful about going over terrazzo floors that have previously used penetrating sealants. We strongly advise that you go back over a repaired area with the same type of sealer and the same chemistry as what is already on the floor.
Are Polyurethane Sealers Compatible With Acrylic Sealers?
Water based acrylic sealers bond very well to water based acrylics and water based polyurethanes bond very well to water based acrylic sealers, BUT those same acrylic sealers do not bond very well to water based urethanes.
This means that if you have an acrylic based sealer already on your floor, and you want to go over it with a urethane sealer, those should bond and your project should work out alright. But, if the circumstances are the other way around, as in you have a urethane sealer on the floor, you will have better luck going over that with another urethane as opposed to using an acrylic.
Also, if you have a solvent based sealer currently on your terrazzo, it is best to go over it again with another solvent based sealer instead of a water based one. Trying to bond the two can lead to a lot of incompatibility issues and a lot of material rejection.
Similarly, going over a water based sealer with a solvent base can damage the water based sealer. So, if you have a water based acrylic and you go over it with a solvent based acrylic, you can damage it. If you have a solvent based urethane and you try to go over a water based acrylic, you can damage it that way too.
It is always best to try and keep the chemistries of your products the same.
Sealing Terrazzo | Summary
We sincerely hope this post has given you the proper insight as to what exactly terrazzo sealer is, as well as the different available options for sealer types and application methods – and most importantly – how to determine which path for terrazzo floor care is best for you.
As always, if you have any questions about which product is the best for your unique situation, call us at: 754-253-3401
FAQ: What Is Burnishing?
So the term “burnishing” differs from buffing or polishing because it’s done at a much higher speed.
When burnishing, we’re using equipment where the circular pad, or the burnishing pad is rotating at around 2000 RPMs, meaning revs per minute. Compare that to a polishing or buffing machine, which generally have around 175 revolutions per minute (RPM).
We tend to refer to buffing machines, as slow-speed machines, as they only make about 175 RPMs. But the burnishing is done at a very high speed – 2000 RPMs or higher. And at that higher speed, you get a much higher shine because you are actually heating the floor sealer and softening it to eliminate scratches and increasing the shine. Burnishing produces a much smoother and shinier surface. It’s with the burnishing process that you can achieve a higher gloss look much better than you can with a slow speed machine.
To clarify, burnishing equipment is not used for stripping; that’s where you use slow speed equipment with a stripping pad moving at a slower speed. The burnishing is more about polishing, and increasing the shine by smoothing out any scratches in the top layer through heat and abrasion.
Often, you’ll see the janitor or contractor go around with an auto scrubber to scrub and clean the floor. Then they’ll come back with a burnishing machine, to burnish it up and increase that shine by knocking out all those topical, minor scratches.
To care for deep scratches, is a matter of repairing that area of the floor.
About Our Expert | Charles Idowu
Charles Idowu started his career as a civil engineer in 1983 in the UK. After achieving his MBA and his Chartered Engineer qualifications, Charles quickly became the waterproofing and coatings expert for a renowned British construction company. His international work landed him in South Florida, where he combined his engineering experience and passion for business to start CoverTec Products.