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How to Clean Unsealed Concrete Floors? A Step-By-Step Guide

Unsealed concrete floors are usually ignored and not cleaned for a longer period of time. The main reason is that these floors are mostly installed in basements, garages, store rooms, and backyard patios. These areas don’t get that much foot traffic, thus people tend to neglect cleaning them. But the question is, how to clean unsealed concrete floors whether it is in a low-traffic area or in your main living area? 

The unsealed concrete floors don’t have a protective, waterproof layer on them. Thus it absorbs liquid spills and gets stained if not cleaned in time properly. Besides getting stained, if the unsealed floor continues to absorb liquid and moisture, it will develop mold and mildew. 

While molds are beneficial for the general environment and we are always exposed to them in the open world, letting them grow in your basement or garage is not a good idea. Molds grow on moisture and release microscopic spores. These spores are very tiny and can easily be inhaled, causing sinus problems among other health issues

An unsealed concrete floor develops cracks in it. These cracks and crevices then become the favorite spot for molds, dust, cobwebs, and all types of debris to accumulate.

How To Clean Unsealed Concrete Floors?

how to clean unsealed concrete floors

So, how to clean unsealed concrete floors whether it is in your basement, garage, or backyard patio? Read along for a step-by-step guide to removing the most common types of stains.

Manual Cleaning

If you haven’t touched your floor for ages, it must have gathered all sorts of debris. 

The first step in cleaning the unsealed floor is to do manual cleaning. Pick up all the large debris that a vacuum cleaner cannot pick up including rocks, leaves, screws, bolts, cloths, or any tool left on the floor of your basement, garage, or backyard patio. 

You will have to use a broom or brush with nylon bristles. Metal bristle brushes should be avoided because they will further deteriorate the unsealed floor. The metal particles of the brush will also deposit in the cracks and pores of the floor and will rust over time.

Use A Vacuum Cleaner

When the manual cleaning is done, you should use a vacuum cleaner to make sure that all the dust particles, grains, cobwebs, and all fine debris are removed even from the cracks and crevices of the unsealed concrete floor. 

You can use the best robot vacuum cleaner for concrete floors that have increased suction power, automatic cleaning, self-emptying dirt bins, and all other smart features that make cleaning a no-one’s job. Smart robot vacuums will navigate over every inch of your floor autonomously picking up the tiniest bits of debris even from cracks and crevices.

Treat The Stains

Once all the debris is picked up, it’s time to come to the main cleaning chore i.e. treating the stains. 

It’s common to have oil and grease stains on your garage or unfinished concrete floor of your basement, and food and drink stains on backyard patios. You might also have rust stains If you have metal furniture on your backyard patio or if you have left some metal equipment on the concrete floor in your garage or basement. 

Different types of stains require different cleaning solutions and techniques.

How To Clean Oil Stains?

Whether your car leaked oil and grease on your garage floor or a lawnmower leaked oil on your backyard patio, these oily stains are common on concrete floors.

You can find many commercial products and degreasers in the market. But before spending cash on these products, try some household cleaners to clean these stains. 

Things you will need
  • Cat litter or sawdust 
  • Vacuum cleaner
  • Baking soda or laundry detergent powder 
  • Warm Water
  • Bristle brush or a scrubber
Oil stain cleaning process

To clean oil or grease stains from your unsealed concrete floor, follow these steps.

  • Sprinkle some cat litter or sawdust on oil spills and leave it until the grease and oil are all soaked up. 
  • Once the excess oil and grease are absorbed, remove the cat litter or sawdust, whichever you used, using a vacuum cleaner. 
  • Take some baking soda or laundry detergent powder and make a paste of it by adding some warm water. 
  • Apply the paste to the oil spill.
  • Use a bristle brush or scrubber to scrub the stained area and agitate the oil and grease out of the concrete. 
  • Leave it for about half an hour.
  • Agitate the stain again with the scrubber. 
  • Rinse the spot with warm water. 
  • Dry it thoroughly.

If the stain is not completely cleaned, repeat the above process. 

If the oil stain is very old and seeped deep into the cracks of your unsealed floor, and the baking soda and laundry detergent don’t have any effect on it, you might have to use a commercial degreaser. Use the above-mentioned steps with a commercial oil stain remover.

How to prevent oil stains?

Prevention is better than cure. Instead of putting in the elbow grease to remove the oil from concrete floors, you should not let the oil spills happen in the first place. Take the following precautionary measures to prevent oil stains: 

  • Seal your concrete floor so it doesn’t absorb oil and grease. 
  • Place a mat under your car during maintenance or repair. 
  • Clean the oil or grease as soon as it is spilled. 
  • Keep an eye on your car or lawnmower for leakage.
  • Keep your car and lawnmowers maintained and serviced regularly. 
  • Never leave any oil bottle uncapped on the garage or basement floor.

How To Clean Paint Stains?

Removing paint from unsealed concrete floors is easy if it is removed as soon as it is spilled. Put some warm water on the fresh paint stain and scrub with a bristle brush to remove it.

But, removing dried paint stains that are left for a long time requires some elbow grease. Concrete absorbs the paint and it sets into the pores of the concrete.

Things you will need
  • Water-based paint stripper
  • Bristle brush or scrubber
  • Warm water
  • Pressure washer
Paint removing process

To remove paint stains from unsealed concrete floors, you will need paint strippers. Normally, there are two types of paints used in the house; water-based and oil-based. So, make sure that the paint stripper you are selecting is recommended for the type of paint spilled on your floor. 

  • Apply a thick layer of the paint stripper to the paint stain using a brush. 
  • Leave the paint stripper on the stain until the paint starts to soften. 
  • Take a bristle brush and scrub the stain until the paint is removed. 
  • If the paint is not removed completely, repeat the process again until the stain is gone. 
  • Once the stain is completely gone, wash the area. Using a pressure washer will be helpful to clear off the gooey mess the paint strippers leave.

There are two types of paint removers available in the market. One is water-based while the other is solvent (methylene chloride) based. 

Use only water-based paint strippers instead of solvent-based ones. The solvent-based paint removers are toxic and can cause health issues if inhaled or contacted with the skin. The water-based paint strippers are eco-friendly and biodegradable.

How to prevent paint stains?
  • Seal the concrete floor. 
  • Place a plastic sheet on the floor when painting the walls. 
  • Place plastic sheets under the paint bucket when placed on the floor. 
  • Remove paint as soon as it is spilled on the floor.

How To Remove Food Stains?

While enjoying a feastful brunch on your backyard patio or having a snack in your garage or basement, food, juice, wine, and other drink stains are common in these places. On an unsealed and unfinished concrete floor, these stains get tougher if not cleaned in time. 

Things you will need
  • Dish soap
  • Laundry detergent 
  • Bristle brush or scrubber 
  • Hot water
  • Mop or microfiber cloth
Food stains cleaning process

To remove food and drink stains, follow these steps. 

  • Rinse the stained area with dish soap to remove any excess oil and drippings.
  • Next, take the detergent powder and make a paste by mixing it with water. 
  • Apply this paste to the stain and leave it for at least an hour. If the stain is deep and old, you might have to leave the paste for as long as overnight. 
  • Now use a nylon bristle brush to agitate the stained area. 
  • Wash with hot water and dry it thoroughly either with a microfiber cloth or with a mop. 

If the stain persists, repeat the above process.

How To Remove Rust Stains?

If you have left metal tools or screws on your unsealed concrete floor in the garage, have metal furniture on your backyard patio or you happen to have scrubbed your floor with a metal bristle brush, the metal particles get stuck in the pores of the concrete. These metal particles, when exposed to water or moisture, rust over time leaving orange-brownish stains on your floor. These rust stains are an unsightly thing especially if they appear on the floor of your main living area. 

The longer these rust stains are left on the floor the harder it is to clean them.

Things you will need
  • Dish soap
  • Safety gloves
  • Safety goggles
  • Lemon juice, white vinegar, or a commercial rust cleaner
  • Bristle brush or scrubber 
  • Hot water
Cleaning process for normal rust stains

If the rust stain is relatively new and normal in size, use the following steps to remove it.

  • Rinse the rusted area with dish soap to remove any dust or grease. 
  • The next step is to treat the rust stain. 
  • If the rust stain is relatively new you should use pure lemon juice or white vinegar. 
  • Pour some on the rusted area and let it sit for at least 15-20 minutes. 
  • Now use a bristle brush to agitate the rusted area. 
  • Next, rinse the spot with hot water and let it dry thoroughly. 

You might have to repeat these steps if the rust stain is not eradicated after the first attempt.

Cleaning process for older and bigger rust stains

If the rust stain is deep and very old and doesn’t get removed even after repeating the above procedure multiple times, you should use a commercial rust cleaner. 

Rust cleaners that include oxalic acid, hydrochloric acid, or trisodium phosphate are especially effective in removing old and deep rust stains. 

Pro Tip

CAUTION should be taken while working with acids. Strictly follow the instructions mentioned on the bottle label. Take precautionary measures by wearing protective gloves, goggles, and proper clothing to avoid any skin burns. 

When using a commercial rust cleaner, follow the instructions mentioned on the label to make the solution as different types of acids require a different level of dilution. 

Once the solution is made, follow the above-mentioned steps used with lemon juice or vinegar until the deep-rooted old rust stains are removed. 

USE proper safety gear while working with acids.

How to prevent rust stains?
  • Never use a metal bristle brush to scrub the concrete floor as the metal particles will deposit in the pores and will rust when exposed to moisture. 
  • Try not to place metal furniture on your floor. If you have metal furniture, place felt pads under the legs. 
  • Never leave any tools or screws on the floor of your garage or basement. 
  • Keep proper ventilation in the basements and try to expose the area to sunlight. 
  • Use a dehumidifier if the sunlight cannot reach the basements or garages.

How To Remove Molds And Mildew?

Moisture causes molds and mildew to grow especially in the cracks of the unsealed concrete floor. Make sure that the floor is properly dry otherwise, the molds will spread their spores in the air which can cause allergic reactions and sinus problems. If you are allergic to mold, wearing a mask is recommended. 

Things you will need
  • Dust mask
  • Safety goggles
  • Safety gloves
  • Scraper
  • Sponge 
  • Bleach, white vinegar, or trisodium phosphate 
  • Rubber gloves
  • Pressure washer
Mold cleaning process

You have two options to create a cleaning solution to remove mold and mildew from your unsealed concrete floor depending on the level of growth. 

  1. The first one is if you have low to moderate mold growth. Mix one cup of bleach with one gallon of warm water to create the cleaning solution. 
  2. The second one is if you have an extreme level of mold and mildew growth. For this, you should add one tablespoon of trisodium phosphate to the above solution of bleach and warm water. 

While working with bleach or trisodium phosphate, keep the area well-ventilated. Use protective gear, goggles, a mask, and proper clothing to avoid any health issues. 

Once the cleaning mixture is prepared according to your needs, follow these steps: 

  • Dry the affected area properly. 
  • If you have an extreme growth of mold, first scrape away as much mold as possible using a scraper.
  • Spray the solution, either the bleach solution or the trisodium phosphate solution, whichever you are using, on the mold.
  • Scrub the area with a sponge soaked in the cleaning solution. 
  • Mop the area with clean warm water. 
  • If the mold is still present, you should make a stronger mixture. Decrease the amount of water to make a stronger solution and start cleaning again. 
  • Once the mold is completely gone, use a pressure washer to wash away all the residue from the floor. 
  • Make sure that the floor is dried thoroughly.
How to prevent mold?

Removing the mold from your unsealed floor doesn’t mean it won’t appear again. You should take the following precautionary steps to prevent mold and mildew from regrowing in the future:

  • While removing the mold from your floor, make sure that the roots of the mold are also removed otherwise, it will grow back again. 
  • Keep the floor as dry as possible. 
  • Expose the area to sunlight if possible. 
  • Properly ventilate the area. 
  • Dehumidify the area if ventilation is not adequate. 
  • Properly seal the floor to fill up all the cracks – the favorite place for molds to grow.

Frequently Asked Questions

Should you mop unsealed concrete floors?

Yes. Unsealed concrete floors can benefit from mopping as it helps to remove dirt, debris, and grime that build up over time. However, it is important to use the right cleaning solution and tools to avoid scratches and scuff marks on your floor. Mopping can also enhance the overall appearance of the concrete floor by making it shiny and removing any streaks and stains. 

What is the best chemical to clean concrete?

Trisodium Phosphate (TSP) is one of the best chemicals to clean concrete floors. It is a heavy-duty cleaning agent that is commonly used to remove dirt, grime, grease, oil, and other stains from concrete floors. It is a strong alkaline cleaner that can penetrate deep into the cracks of the concrete to dissolve tough stains and provide a thorough cleaning. CAUTION should be taken while using TSP for cleaning purposes and follow the instructions strictly. 

Does vinegar clean dirty concrete?

Vinegar is a versatile cleaning agent that can be used to clean a variety of surfaces, including dirty concrete. Its acidic properties make it effective in removing dirt, grime, and stains from your floors. 

Can you use hydrochloric acid to clean concrete?

Hydrochloric acid, also known as Muriatic acid, can be used as a cleaning agent on concrete due to its effectiveness in removing tough stains. However, it is important to handle it with care as it is a strong and potentially hazardous substance. Always wear protective gear and follow the manufacturer’s instructions when using acids. 

Can I leave concrete unsealed?

While it is possible to leave your concrete floor unsealed, it is recommended to apply a sealer to protect the surface and prolong its life. Leaving your concrete floor unsealed means that the surface is not protected from staining and wear and tear over time. This can result in the concrete becoming stained, discolored, and prone to cracking and chipping. Concrete floors used in a high-traffic area or in outdoors are more susceptible to damage without proper sealing. 

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