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Should you wet concrete before sanding?

Make sure to wet the surface and wipe away excess dampness to rid the flooring of dirt. Countertops can be swept and vacuumed clean. Then a concrete cleaner can be used to wipe it down completely. This prevents any texture issues caused by dirt getting in the way of the sandpaper.

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Concrete floors are rising in popularity, and contractors are finding themselves asked to use concrete in new ways. From floors, garages, basements, counters, and outdoor fixtures, sanding concrete is the "it" thing. Learning how to sand concrete is therefore a necessary skill for commercial flooring contractors to have in their arsenal. Brush up on your skills with this helpful overivew.

When Do You Sand Concrete?

There are a few times where you may be asked to sand concrete on a job. Lately, it's often for interior surfaces. You can sand concrete to achieve a polished, sophisticated look. Sanded concrete can create a very modern, high-end look for an industrially-styled space. This may be applied to floors in office buildings or modern homes. Another great place to integrate sanded concrete into home decor is countertops. Sanding concrete counters to a high shine is how you can instantly elevate them - for a fraction of the cost of granite or marble. It may also be time to sand concrete if you are removing a finish or looking to apply a new coat of finish. As paint, epoxy, and polyurea garage and basement floor sealants become more popular, you may end up sanding concrete to prepare for this. Sanding concrete can help you get rid of imperfections as well. If a garden wall has chipped or the patio has gotten stained, sand to remove the blemish. Make sure to sand the entire surface at once for a consistent texture. This is a good tip to remember during concrete installation.

What Tools Work Best for Sanding Concrete?

When you learn how to sand a concrete floor or counter, you have many tools at your disposal. From basic sandpapers to power tools, you can achieve the polished look you want with reasonable effort.

Sanding by Hand

You can sand concrete by hand. However, doing so likely depends on the amount of space you need to polish. How big of a space you're willing to do this in is up to you. Working with 30 to 60 grit sandpaper, use smooth, even strokes to sand down the target area.

Sanding with Power Tools

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The orbital sander is an ideal tool to use when sanding concrete. This will reduce your effort significantly and give a consistent polish to the counter or fixture. The one downside is how they are handheld with relatively small faces. If you are sanding an entire concrete floor, look for something larger. For wide floor spaces, use a floor sander - also known as a drum sander or a concrete grinder. These can be operated standing up. These typically can attach to a vacuum for mid-project cleaning. Concrete grinders have diamond bits for the hardest possible sanding material. These are used both to remove any lingering paint or epoxy coating and then to polish the concrete.

How to Sand Concrete

*Employ proper safety techniques and equipment during concrete sanding, including masks, safety glasses, and a dust removal system (preferably a vacuum attached to the sander itself).*

Materials You Need

Sandpaper and/or diamond pads

Water bucket and mop

Orbital sander or floor grinder

Vacuum

Epoxy resin or concrete sealant of choice

Prepping the Concrete

For both flooring and smaller surfaces, make sure to thoroughly clean the concrete before you begin the process of sanding. You may need to start removing paint or sealant with a grinder first. Flooring can be cleaned with a thorough vacuuming, followed by mopping. Make sure to wet the surface and wipe away excess dampness to rid the flooring of dirt. Countertops can be swept and vacuumed clean. Then a concrete cleaner can be used to wipe it down completely. This prevents any texture issues caused by dirt getting in the way of the sandpaper. As you prep the concrete, prep anything else in the space that you don't want concrete dust all over. Though it is ideal to have a vacuum attached to your sander as you go, some dust may escape. Plastic sheeting over furniture or hung in doorways prevents the unwanted spread of dust.

Fix Holes

Before you get started, patch holes with concrete slurry. If you overflow these a little, you will soon be able to sand it down with the sander or sandpaper. Color-matching any filling material is suggested. When dry, it will be extremely noticeable if not matched to the original concrete color.

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Sanding

This is where the real work begins. You should have your materials arranged to start work. On the clean surface of your countertop or small concrete space, use long strokes with the sandpaper to bring it to a polished, level texture. You can go in circles as you might with other sanding techniques. Work from one corner out in straight lines or circles. A similar pattern should be used with power tools like an orbital sander or floor sander. While using your floor grinder and polisher, grid out the floor so that you can work it in a logical manner. Work in up-and-down lines or circles from one corner to the opposite. Ensure smoothness by passing back over each stroke partway as you complete the next. It is helpful to use water to wipe away particulate as you go. Dampness can help you see if there are any spots you have missed. For areas with uneven texture, use up-and-down continuous motion to smooth it. Leaving the sander in the same spot will cause un-evenness, but steadily moving it back and forth over the same spot should smooth it out.

Finishing

Finishing requires a final rinse with water to clear away any dust and reveal uneven spots. Once the concrete dries from this final rinse - how long this takes is up to two days - you can apply a final sealant of your choice. Epoxy resins are a popular option. However, you will need one to three days to let it dry.

Shop With OnFloor Technologies

For all your sanding concrete contracting needs, Onfloor Technologies has the materials you need for sanding concrete. We also offer a wealth of knowledge about pouring, designing, finishing, and how to sand concrete. When you start a concrete project with Onfloor technologies, you have excellent equipment and industry knowledge at your fingertips.

Shop concrete floor sander options and more on Onfloor.

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