Mechanical grinding involves removing the smooth top layer to expose the raw concrete beneath. An industrial grinder equipped with diamond grinding blocks or a hand grinder using diamond discs is typically used for mechanically grinding the floor surface. Grinding makes controlling the surface profile easier, and it also helps to ensure a consistent result for the necessary texture to be achieved.
Depending on the requirement of the manufacturer for the coating, a concrete profile similar to 60 to 120 grit sandpaper is needed to ensure proper bonding. Grinding can leave uneven areas and gouge marks on the floor if it is not done properly. You should hire a professional floor coating company for a consistent and well-profiled surface.
Acid Etching
Acid etching involves the application of acid to remove the top surface of the concrete floor. This method is good enough to prepare the floor for the application of protective coating especially if you are thinking of a DIY project or new concrete. Acid etching can expose the pores of the concrete under ideal circumstances but it won’t remove glues, caulks, mastics, and other common stains. If your floor is stained by any of these substances, you will need to clean the floor first to remove them.
The etching process can leave behind a wet concrete dust film that might clog the concrete pores if not fully cleaned off; this can lead to coating failure. Additionally, if the acid is not properly disposed of it can damage paving stones, landscapes, grass, etc.
Which One is Better?
Acid etching a garage floor is a great solution for those who are installing the floor themselves and do not have access to industrial grinders. However, for larger commercial jobs, older concrete, or worn floors we always recommend grinding before epoxy installation. This is because there are different concrete types with varying composition, texture, and hardness levels. This means there is not a one size fits all solution.
Diamond grinders use several grinding heads designed for the variations in concrete surfaces to ensure you get a proper surface profile that lasts a lifetime. Acid etching is a better option than power washing but it doesn’t give the same results as grinding.
Anyone with a decent commercial floor paint product and a little DIY skill can coat a garage floor and get a great end result. The concrete floor will fail if the coating doesn’t bond mechanically to the concrete floor, so the preparation is the most important part before applying any type of epoxy! So it is important that there is a solid bond between the concrete and epoxy coating so as not to end up with a failed epoxy garage floor.
19 Responses to “Grinding vs. Acid Etching Your Concrete Floor”
Seelan PillayOctober 16, 2020 at 10:15 amPermalink
I have concrete floors that i want to epoxy paint, i was told my floors are to smooth, needs to be sanded down before i paint, please advise and render your service if you can
It’s great that you explained how grinding helps remove unwanted stains on your concrete floor. My wife and I are looking at house options, and we found the one that had everything we wanted, but we realized it has an awful stain on its driveway. We were thinking about backing out, but after reading your piece, we think we still have hope for getting our dream home. We’re grateful for your tips about how to successfully remove stains from your concrete floor.
Grinding is a process that removes thousandths of an inch from the surface using diamond-embedded blades, and will remove ‘surface stains and such. If the surface is very stained where oils have soaked deep into the concrete, there is no way to easily remove them. But…a solution would be to simply coat over them to cover the stains with the Armorpoxy Surface Bond Coating. Available in over 50 colors to match most any landscaping and house colors.
I had my concrete porch painted. They cleaned, applied muriatic acid, cleaned again, then after it was dry applied HD porch and concrete paint. Within a month it was peeling. I had to have it power washed off. What a mess! Back to square one. It looks awful in the original concrete. How can I successfully paint it? Is it better to stain it?
If you are having issues with peeling most likely this was due to improper prep or moisture issues. A stain is much less prone to peel as it absorbs into the concrete as opposed to sitting on top of it. We would recommend removing the old coating, and grinding it with a diamond floor or hand grinder. Vacuum well and recoat with something like our ArmorTop Acrylic Epoxy or a stain if you want that look. Stains though do nothing to protect the surface so if you live in an area where it freezes, best to put on a topical coating for protection.
My garage floor has an oil spill about 5 feet in diameter. How should I prep this floor. The garage is only 6 years old and I want to use the best multilayer epoxy available or other sealant available. I am not concerned if it takes multiple days to complete the project. I am very good at doing my own projects.
Alex - ArmorPoxySeptember 8, 2021 at 12:06 amPermalink
Hi Curtis,
You will first need to remove the spill spill to the best of your ability. You can do so by diamond grinding and trying to take away as much of the spill as possible. I would then suggest using a three layer epoxy coating system and if you like the look of a full broadcast flaked system this will help in making sure the oil spill does not penetrate through the final coating.
Take a look at our different Job on a Pallet DIY Coatings kits in which we supply you with everything oyu need to install a new epoxy floor.
We built our home in 2016, had all flooring (3,200sf) stained concrete. We was told it would be very durable and mostly scratch resistant with have 3 kids. Since day 1 every little thing scuffs and scratching the floor. We was thinking of painting it with a concrete/ porch paint. What steps or route should I take with etching or should we sand it? It will be a diy project.
Alex - ArmorPoxySeptember 7, 2021 at 11:57 pmPermalink
Hi Winter,
Unfortunately stained concrete can sometimes lead to more scratching. We would suggest diamond grinding or sanding followed up with a epoxy coating. Acid etching will not suffice ad a prep as the floors needs to have some grip to it to allow for a coating to adhere properly.
I have fairly newly poured concrete that is smooth and possibly lightly sealed. Must I grind it before epoxy or can I get away with just etching? Thanks
Alex - ArmorPoxySeptember 24, 2021 at 7:29 pmPermalink
Hi Jacob,
We would suggest that you grind the floor to a min CSP 2. Acid etching will suffice but you will get a better bond if you diamond grind. Make sure to wait at least 30 days before grinding and beginning any epoxy application.
why do you need to wait 30 days before epoxy after grind.
The 30 day waiting period relates to newly-poured concrete. Please note that some concrete can take much longer to cure based on temperatures, type of pour, thickness, humidity, etc. Once cured the concrete should be prepped by grinding or etching, then can be coated right away. There is no wait between grinding and applying a coating.
Whats the difference between surface bond and armor top?
I have a year old, outdoor smooth surface concrete slab and i m having issues with the concrete slab to be very dusty all the time.I would like to apply a more durable sealer/paint such as epoxy rather than just concrete paint.I need something that wont change color or get yellowish like indoor garage epoxy.
Please advise what products i need for this project.
We would suggest our Armor Renew product. Armortop is unfortunately being discounted and Surface Bond is much more Heavy Duty application for vehicular traffic areas on concrete and asphalt.
Please take a look as this product is easy to roll out and offers great protection against the sun. It’s also a much thicker coating than what we would suggest for an epoxy floor as it comes naturally textured giving the floor great slip resistant and durability.
What happens if epoxy or paint is applied to a garage floor which has been self-levelled but not had grinding or acid etching applied? And what’s the likelihood of it happening?
We has a contractor recently renovate our garage. Self levelling concrete was used and then polyurethane paint applied (2 coats). It looks great now after several weeks but from reading these comments I am now concerned.
It’s always best to prep the surface no matter if its new concrete, self leveler, etc. Reason being is that even though the self leveler is new and clean it should still be profiled to maximize the coatings adhesion. With no prep it’s possible the coating did not get as good a bond as possible but that does not mean it will not adhere well and last for years to come. There’s no way of telling now but in the future it’s best to prep the floor by mechanical means (sanding, diamond grinding, shot blasting, etc.) to guarantee proper adhesion.
I used epoxy for my garage. Prior to applying the epoxy, I used the concrete etch. Unfortunately when I was squeegeeng the acid etch out of my garage I did not rinse properly, which left acid etch stain on my driveway. Any advice on how to remove the acid etch residue from my concrete driveway?
I ground my garage floor using a diamond cup wheel and it’s very clean but also very smooth. The scratches are minimal and barely seen in areas.. Should I use a different wheel? The floor is nothing like sandpaper.
I have concrete floors that i want to epoxy paint, i was told my floors are to smooth, needs to be sanded down before i paint, please advise and render your service if you can
Feel free to email us at info@armorpoxy.com and we would be happy to make a product recommendation.
It’s great that you explained how grinding helps remove unwanted stains on your concrete floor. My wife and I are looking at house options, and we found the one that had everything we wanted, but we realized it has an awful stain on its driveway. We were thinking about backing out, but after reading your piece, we think we still have hope for getting our dream home. We’re grateful for your tips about how to successfully remove stains from your concrete floor.
Grinding is a process that removes thousandths of an inch from the surface using diamond-embedded blades, and will remove ‘surface stains and such. If the surface is very stained where oils have soaked deep into the concrete, there is no way to easily remove them. But…a solution would be to simply coat over them to cover the stains with the Armorpoxy Surface Bond Coating. Available in over 50 colors to match most any landscaping and house colors.
I had my concrete porch painted. They cleaned, applied muriatic acid, cleaned again, then after it was dry applied HD porch and concrete paint. Within a month it was peeling. I had to have it power washed off. What a mess! Back to square one. It looks awful in the original concrete. How can I successfully paint it? Is it better to stain it?
If you are having issues with peeling most likely this was due to improper prep or moisture issues. A stain is much less prone to peel as it absorbs into the concrete as opposed to sitting on top of it. We would recommend removing the old coating, and grinding it with a diamond floor or hand grinder. Vacuum well and recoat with something like our ArmorTop Acrylic Epoxy or a stain if you want that look. Stains though do nothing to protect the surface so if you live in an area where it freezes, best to put on a topical coating for protection.
My garage floor has an oil spill about 5 feet in diameter. How should I prep this floor. The garage is only 6 years old and I want to use the best multilayer epoxy available or other sealant available. I am not concerned if it takes multiple days to complete the project. I am very good at doing my own projects.
Hi Curtis,
You will first need to remove the spill spill to the best of your ability. You can do so by diamond grinding and trying to take away as much of the spill as possible. I would then suggest using a three layer epoxy coating system and if you like the look of a full broadcast flaked system this will help in making sure the oil spill does not penetrate through the final coating.
Take a look at our different Job on a Pallet DIY Coatings kits in which we supply you with everything oyu need to install a new epoxy floor.
Thanks,
The Armorpoxy Team
We built our home in 2016, had all flooring (3,200sf) stained concrete. We was told it would be very durable and mostly scratch resistant with have 3 kids. Since day 1 every little thing scuffs and scratching the floor. We was thinking of painting it with a concrete/ porch paint. What steps or route should I take with etching or should we sand it? It will be a diy project.
Hi Winter,
Unfortunately stained concrete can sometimes lead to more scratching. We would suggest diamond grinding or sanding followed up with a epoxy coating. Acid etching will not suffice ad a prep as the floors needs to have some grip to it to allow for a coating to adhere properly.
Thanks,
The Armorpoxy team
I have fairly newly poured concrete that is smooth and possibly lightly sealed. Must I grind it before epoxy or can I get away with just etching? Thanks
Hi Jacob,
We would suggest that you grind the floor to a min CSP 2. Acid etching will suffice but you will get a better bond if you diamond grind. Make sure to wait at least 30 days before grinding and beginning any epoxy application.
why do you need to wait 30 days before epoxy after grind.
The 30 day waiting period relates to newly-poured concrete. Please note that some concrete can take much longer to cure based on temperatures, type of pour, thickness, humidity, etc. Once cured the concrete should be prepped by grinding or etching, then can be coated right away. There is no wait between grinding and applying a coating.
Whats the difference between surface bond and armor top?
I have a year old, outdoor smooth surface concrete slab and i m having issues with the concrete slab to be very dusty all the time.I would like to apply a more durable sealer/paint such as epoxy rather than just concrete paint.I need something that wont change color or get yellowish like indoor garage epoxy.
Please advise what products i need for this project.
Hi Jay,
We would suggest our Armor Renew product. Armortop is unfortunately being discounted and Surface Bond is much more Heavy Duty application for vehicular traffic areas on concrete and asphalt.
Please take a look as this product is easy to roll out and offers great protection against the sun. It’s also a much thicker coating than what we would suggest for an epoxy floor as it comes naturally textured giving the floor great slip resistant and durability.
Thank you,
The Armorpoxy Team
What happens if epoxy or paint is applied to a garage floor which has been self-levelled but not had grinding or acid etching applied? And what’s the likelihood of it happening?
We has a contractor recently renovate our garage. Self levelling concrete was used and then polyurethane paint applied (2 coats). It looks great now after several weeks but from reading these comments I am now concerned.
Many thanks!
Hi Dom,
It’s always best to prep the surface no matter if its new concrete, self leveler, etc. Reason being is that even though the self leveler is new and clean it should still be profiled to maximize the coatings adhesion. With no prep it’s possible the coating did not get as good a bond as possible but that does not mean it will not adhere well and last for years to come. There’s no way of telling now but in the future it’s best to prep the floor by mechanical means (sanding, diamond grinding, shot blasting, etc.) to guarantee proper adhesion.
Thanks you,
The ArmorPoxy Team
I used epoxy for my garage. Prior to applying the epoxy, I used the concrete etch. Unfortunately when I was squeegeeng the acid etch out of my garage I did not rinse properly, which left acid etch stain on my driveway. Any advice on how to remove the acid etch residue from my concrete driveway?
I ground my garage floor using a diamond cup wheel and it’s very clean but also very smooth. The scratches are minimal and barely seen in areas.. Should I use a different wheel? The floor is nothing like sandpaper.