The preparation of the surface before applying epoxy flooring is an essential step that often determines the success and durability of the installation. Understanding the right techniques is vital, especially when a professional grade installation is expected.
Here's a guide to properly preparing your surface with an emphasis on professional preparation methods over insufficient processes.
Professional Level Concrete Preparation Methods:
Concrete Grinding: The most common method involves using a concrete grinder fitted with diamond grinding tooling known in the industry as “Diamonds” and “Cup Wheels”. Grind to remove light contaminants such as paint drippings, drywall mud, the daily buildup of light contaminants such as oil, grease, and road tars, as well as the smooth shiny crust on top of the concrete. This will open up the pores of the concrete, so the epoxy can bond to it. If you don’t do that it’s not going to last.
Diamonds are also used to remove an existing coating such as epoxy or paint, and small surface imperfections. Concrete grinding machines also create a smooth and even surface while removing most surface contaminants and opening up the pores of the concrete, so the epoxy can bond to it. Grinding will not remove any oil saturation. Oil saturation requires other time consuming and often expensive means of removal or sealing it in. Concrete grinding is the preferred method for both professionals and DIYers that want a proper epoxy floor installation. Grinding ensures optimal adhesion and a long-lasting finish.
Shot Blasting: Shot blasting involves propelling small steel BB’s at high velocity onto the concrete surface, effectively removing dirt, coatings, and imperfections while profiling the concrete for your resinous material application. This method provides an excellent profile for the epoxy to adhere to and is often used in industrial settings for optimal preparation. Many manufacturers recommend shot blasting to prepare the concrete for the application of Moisture Vapor Barrier (MVB).
Amateur Level Concrete Preparation Methods:
For those weekend warrior DIYers that take their projects seriously but don’t want to rent a concrete grinding machine and vacuum but want to do the best you can for an affordable price, you can use a Diamabrush. For homeowners and smaller projects, renting a Diamabrush can be a suitable option for some applications and I stress the word “some”. This is an “ok” fit for concrete that is NOT contaminated with any significant amount of oil or grease. However, it simply will not level the floor and it will not grind in an significant way.
This tool attaches to a standard floor buffer aka a swing machine and can abrades (not grind) the surface to a more acceptable level than pressure washing, or acid etching methods to help the epoxy bond better. Again, this is not a substitute for a professional grade concrete grinder or shot blaster but it can help a competent DIYer install a new epoxy garage floor. This method provides an adequate level of preparation without needing professional-grade equipment.
Methods to Avoid:
While some methods might seem suitable for preparing a surface for epoxy, they fall short in providing the right conditions for optimal adhesion and durability. The following methods are often recommended on the DIY kits sold at the big box stores. These kits are nothing more than enamel paint. To the best of my knowledge those kits no longer contain any epoxy anymore. Years ago when they did it was really nothing more than a marketing gimmick because the front of the box would say EPOXY in big bold letters and down in the corner in very small print were the words “contains 3% epoxy”. So it was just a marketing gimmick.
Pressure Washing: Although pressure washing may clean the surface it certainly does not provide the proper profile needed for epoxy to bond effectively.
Acid Etching: Acid etching is just another big box DIY method to install your own “epoxy PAINT floor”. The fact that Acid etching is difficult to control and may leave you with an inconsistent surface profile is the least of your worries. Do I really need to point out that this is hazardous to your health and washing all that acid into your grass or the storm sewer is anything but environmentally acceptable?
Sanding: Sanding might remove some superficial dirt or paint, but it does not create the textured surface necessary for epoxy to adhere properly. It often leaves behind dust that hinders bonding. I’ve run 16 grit sanding disk on a 17 inch swing sander just to see if it will do anything at all. It literally would not even scratch the concrete surface so save your money.
Conclusion:
Proper preparation of the surface before applying epoxy flooring is crucial. Concrete grinding and shot blasting are the only 2 methods of prep work acceptable for a professional level installation. No manufacturer will warranty the bond of a product applied to a floor that is not ground or shot blasted. These two methods provide the right surface profile and ensure a strong and durable bond. DIYers can rent a Diamabrush for a very reasonable price for 4 hours and avoid useless methods like pressure washing, acid etching, and sanding, as they will lead to subpar results and potential issues down the road.
