Gone are the days when polished and stained concrete floors were only used in factories, commercial buildings, sports hubs, and other industrial spaces. Today, you can find it in modern residential spaces. In fact, it has become a trend thanks to its chic and minimalist look that blends well with all sorts of interior designs. 

And perhaps, you are planning to replace your old flooring and turn it into concrete flooring instead? Good thing because finished and stained concrete floors are quite an easy job to do.

That being said, here’s a complete step-by-step guide on how to finish concrete floors.

A Step-by-step Guide to Polishing Concrete Floors

The process of polishing and staining concrete floors is divided into three parts. First is preparation and assessment, second is leveling and grinding, and third is polishing and staining. 

Step 1: Prep the Floor

It is important to prepare the surface first when you are about to stain and polish before anything else. And for this phase, you have to do three important tasks: clean, assess, and repair. 

Here’s how you can do each of them correctly:

Cleaning the area or surface you are about to work on is extremely important when it comes to masonry as dust and tiny debris could impede the process and even mar the finished work’s overall appearance. 

That said, simply scrub the floor using a brush. You can either use warm water or a mixture of water and soap as a solution too. A mild household cleaner works also if you prefer one.

For stubborn dirt and stains, on the other hand, you can use either ammonia, TSP, or hydrogen peroxide. Make sure that you are wearing the right protective gear and that the area is well-ventilated when using any of the said agents as they are toxic and highly flammable.

Next is to check the surface for damages or any hazard spots. Cracks, for example, must be patched and repaired first before grinding the floor. Small pieces of metals that are sticking out must be pulled or cut out. The same rule applies to protruding metal bars as well.

It is best to hire a professional for the job too, especially if you are not familiar with any of these.

Lastly, fill and repair the cracks using a filler or patch solution. For small cracks, a concrete filler and a caulk gun would do. But for larger fissures, it is best to use a vinyl concrete patch.

Step 2: Even Out the Surface Using a Grinder

Grinding concrete is perhaps the most meticulous and difficult part of polishing and staining concrete floors. It requires repetitive tasks that will certainly consume your time and strength, specifically the grinding part.

Not all concrete has the same degree of toughness. As such, evaluating the Measurement of Hardness Scale (MOHS) of the concrete you are planning to finish is extremely crucial as it will dictate what type of concrete grinder is suitable to use with it. 

For instance, if your concrete is soft, the required grinding disc is 5.5 or lower. On the other hand, if you got medium to hard concrete, the recommended grinder is 6.5 or 7.5 and above, respectively.

To do this, you need to purchase a set of MOHS picks. Test the concrete by gently drawing a line using your choice of pick then touch the surface. If you feel a visible scratch, keep working on other picks. You can start on #9 and work your way down or vice versa until you find a pick that does not leave a scratch on the concrete. That will then your floor’s MOHS. 

After the MOHS test, it’s time to start grinding. Concrete grinders are typically available for rent. Look for one with a complete set of discs, ranging from 40-grit to 3000-grit. Also, make sure to get the right level of grinder based on your floor’s MOHS test. It is best to get metal-bonded diamond discs too instead of non-diamond discs. 

Once you have everything complete, you can now start grinding your floor. 

  • Grind the surface using a 40- or 80-grit disc. If your floor has stubborn stains and marks that are too difficult to remove, you may start grinding the concrete using a 40- or 80-grit disc. This can help lift off stains and, at the same time, serve as an initial grinding.
  • Grind the surface again using an 80- to 400-grit disc. Repeat the first step but this time, use 80- to 400-grit discs. Use each disc by their level. You can start with an 80-grit disc then replace it with 150-grit after. Change the disc accordingly until you are done grinding the surface using a 400-grit disc.
  • Apply a densifier. Once done, start applying a concrete densifier evenly on the floor. It is a liquid chemical solution that hardens concrete, which makes the floor less porous. Spraying it will prevent the development of powdery dust too, particularly while grinding.
    Do take note that the application of densifiers depends on the level of MOHS too. For concrete that is soft, for instance, the recommended time to apply the solution is after grinding it using an 80-grit disc. For medium and hard concrete, on the other hand, the best time is after using 200-grit and 400-grit discs, respectively.
  • Do the final grind using a 3000-grit disc. After the application of the densifier, it is time for the final grinding. This time, you have to use a 3000-grit disc.
    However, if you skip this part and jump immediately to staining and polishing, you may also do so. It is because the sole purpose of grinding the floor using the highest level of grinder disc is to further enhance the glossiness of the floor. 

The last part of the grinding process, of course, is to remove all the dirt and debris and most importantly, clean the dust off concrete floors post-grinding. Grinding produces dust and debris that could ruin the appearance of the floor if not cleaned. 

You can simply use a broom and a mop. But it is best to use a wet-dry vacuum as it is more efficient, convenient and makes the process a lot faster. 

Step 3: Floor Staining and Polishing

Finally, it is time to stain and polish your concrete floor.

  1. Burnish. This is optional but if you wish to smoothen out the surface further, replace the disc with a burnishing pad. It will help enhance the smoothness of the floor and make it look more polished. You don’t need to buy one too as it is usually available for rent. 
  2. Apply a staining solution. This step is optional too. However, if you prefer a more vibrant look for your concrete flooring, then you should use a stain or coloring solution. Concrete stain solutions come in a wide array of colors. Prosoco’s GemTone Stain, for example, comes in 25 different tones—ranging from rose quartz to emerald. The stain penetrates deep into the concrete too, which means it will not easily flake and peel.
  3. Seal the floor. Next—and the most important part—is the sealing of the concrete. It is a solution formulated specifically to protect concrete floors from grease, stains, and dirt. The application of it, such as the LS premium concrete sealer, makes the surface glossier as well.
  4. Burnish the floor again. Finally, you can opt to burnish the stained and polished concrete floor for additional and final touch again. Then that’s it! You are all done.
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Matt Greenfield

Matt Greenfield is an experienced writer specializing in home improvement topics. He has a passion for educating and empowering homeowners to make informed decisions about their properties. Matt's writing focuses on a range of topics, including windows, flooring, HVAC, and construction materials. With a background in construction and home renovation, Matt is well-versed in the latest trends and techniques in the industry. His articles offer practical advice and expert insights that help readers tackle their home improvement projects with confidence. Whether you're a DIY enthusiast or a seasoned professional, Matt's writing is sure to provide valuable guidance and inspiration.

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