How to Clean Unsealed Concrete Floors and Remove Stains

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how to clean unsealed concrete floor indoor and outdoor

Unsealed concrete is porous and prone to stains such as mildew, mold, grease, rust, and even common beverage spills. Whether it is your basement, countertop, or garage, improper cleaning of unsealed concrete can leave permanent stains. So, what is the best way to clean unsealed concrete floors?

Sweep off all the loose dirt using a push broom and then mop the concrete floor using a dust mop to remove any fine dust left behind. Sprinkle powder detergent or baking soda on the stained areas and leave it to sit for 1 hour before scrubbing with a brush, mopping, and rinsing.

Concrete’s porosity makes it prone to the absorption of dirt. Unsealed concrete is even more vulnerable to stains as it easily soaks up liquid dirt due to its porous nature. As such, it’s necessary to clean your floor surface every so often using the right method.

In this guide, you’ll learn how to clean unsealed concrete floors and remove different types of stains including grease, oils, beverage spills, and common dirt such as dust and debris.

How to Clean Unsealed Concrete Floors

how to clean unsealed concrete floor indoor

Depending on the type of dirt or stain there is on your concrete garage floors, driveways, countertops, or other indoor floors, you might want to use sawdust, baking soda, and/or powdered dish detergent.

Here’s a step-by-step guide to clean unsealed concrete floors and remove stains:

1. Sprinkle sawdust on grease and oil stains

Collect some sawdust and sprinkle over grease or oil stain spots on your concrete floor (if there are any). Leave it in place for up to 12 hours to completely soak up the grease or oil-based dirt.

This step is great if you want to remove any grease, oil, or other types of stains that are soaked into the porous surface of unsealed concrete. If you do not have any such stains, you can skip this step.

2. Sweep the floor with a push broom

After the 12-hours have elapsed, sweep the sawdust debris from the floor using a sturdy push broom. This will get rid of any loose dirt off the unsealed concrete floor and prep it for vacuuming or dust mopping.

If you skipped the first step, you still need to sweep the floor to remove any large particles and grit that are visible on the concrete before proceeding with the cleaning process.

3. Dust mop or vacuum the floor

Dust-mop the unsealed concrete surface to remove any leftover grit and fine dirt particles. You may also need to vacuum using a vacuum with a fine brush attachment for a much thorough cleaning process.

At this point, most of the oil and grease dirt will be gone but the stain spots may still be visible.

4. Apply detergent and water on the stains

Next, work on the stain spots by moistening them with water and then apply some detergent on the surface. Leave the detergent in place for about an hour to allow it to absorb into the stains.

Detergent contains properties that can break down and remove stains including those of oil and grease.

5. Scrub the stained spots with a brush

Next, use boiled water and a scrubbing brush to thoroughly work the detergent into the concrete and eliminate any remaining stains.

Since concrete floors are porous, a scrubbing brush will help the detergent reach into the tiny openings and break down the stains.

6. Mop with a baking soda solution

Next, pour 2-ounces of baking soda into a one-gallon hot water mop bucket, then mix the solution. Dip a well-wrung mop into this solution and use it to clean off the cleaning residue from the previous step off your unsealed concrete floor.

7. Rinse and wipe the floor dry

Finally, use a dry piece of clothing or towel to wipe the floor surface dry.

how to clean unsealed concrete floor outdoor

Meanwhile, for unsealed outdoors concrete surfaces like concrete patios, driveways, and garage floors, the recommended cleaning procedure is a bit different;

  1. Sprinkle some cat litter over the grease/oil stain spots on your concrete driveway/garage floor. Cat litter is a good grease/oil absorbent.
  2. Next, use a garden hose pipe to apply clean water all over the floor, while scouring tough stain spots with s stiff broom or concrete scouring brush. Alternatively, you can use your pressure pipe to blast water jets over stains to remove them.
  3. If the above steps don’t help you to get rid of all the dirt/stains on your unsealed garage floor, use a commercial heavy-duty concrete floor cleaner and a sponge mop to get to the difficult spots.
  4. Finally, for spots with heavy dirt pile-up, you can use a pressure cleaner to get the job done.

Can you mop unsealed concrete? 

Just like tiled surfaces, unsealed concrete floors are highly porous. Such surfaces can be cleaned using a steam mop, as the steam is able to easily work out oil and grease debris from the permeable structure. Can you steam mop an unsealed floor? Steam floor mops boast immense clean power and handling convenience. However, when using a steam mop on your unsealed concrete floor, you may want to take the following into account;

  1. As a safety measure, ensure to attach the cloth to the mop foot before plugging it into your mains. Also, never attempt to fill in the mop’s water reservoir while the mop is still plugged into the socket, due to the risk of electrocution.
  2. Also, when using a steam mop, remember that the reservoir is meant to hold water alone and not any other concrete surface cleaning agents like muriatic acid solutions or commercial heavy-duty concrete floor cleaner solutions. The steaming effect is usually effective enough to get rid of cement floor stains and as such, no extra cleaning formulae are needed when cleaning using this equipment.
  3. Avoid steam-mopping your unsealed concrete on spots that are near cold fixtures like porcelain sinks that may crack if hot steam is sprinkled onto them.

Leaving your concrete floor unsealed makes it vulnerable to stains as it will easily soak up liquid dirt due to its porous nature. As such, it’s necessary to clean your unsealed concrete surface every so often to eliminate the stains.

How to know your concrete floor is unsealed?

Since unsealed concrete floors are best cleaned using cleaning methods that are different from those used on sealed concrete floors, it’s advisable to determine whether your floor is sealed or not before proceeding to clean it.

  • The easiest way to check for sealer on your concrete floor is through a water-drop test, whereby small drops of water drip over various sections of the concrete surface. If beading occurs and there’s minimal change to the shade of the concrete, then you can conclude that your concrete floor has been sealed. On the other hand, if the concrete surface assumes a darker shade and quickly soaks up the water drops, then what you have is the bare concrete that hasn’t been sealed.
  • However, if you’re getting mixed results from the water-drop test, there are other tests you can use. For instance- for hard-troweled, unsealed concrete, the barely porous, smooth finish may cause water drops to bead on the surface for long, giving the illusion of a sealed surface. If this is the case, try testing the concrete with a muriatic acid solution.

Bubbling and fizzling of the solution is an indicator that the surface lacks sealer material. On the other hand, if nothing happens, then you can conclude that your power-troweled surface is definitely sealed as well.

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Joe McGuinty
I’ve been working with floors for over 12 years. I started as a flooring contractor, primarily in materials selection. Then, I switched careers into accounting, so my wife and I began buying, renovating, and re-selling homes on the side. You’d be surprised how much value you can add to a home simply by adding new floors.

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