Preparing Large Surface Areas for an Epoxy Coating


By Eric Myers, Equipment Development Company

Epoxy coatings are a leading option for garage floors, shop floors and other large areas because of their ability to withstand the effects of stains, abrasive impacts, traffic and heavy equipment. But for the coating to be truly effective and hold up against the normal rigors of life and work, the entire epoxy overlay installation must be done correctly.

This can seem daunting, especially when large areas must be completed in a limited time. The process for properly retrofitting a surface with an epoxy coating comprises several steps.

First, make sure you have or can get all proper equipment—from machines to accessories. Using the proper equipment, such as a concrete grinder, substantially expedites the process and makes the surface preparation step a much easier undertaking.

The Magna-Trap Turbo-Lite Grinder TL-9, folded for transport

EDCO’s 9-inch Magna-Trap Turbo-Lite Grinder (model TL-9) is especially convenient for large, open areas. The TL-9 and other turbo grinders allow users to grind hundreds of square feet per hour, working at a rate five times faster than traditional grinding machines.

But a complete surface preparation project includes tight areas where the floor meets vertical surfaces, such as beams, steps, walls and corners. For those areas, some think their only option is a hand grinder. Instead of getting into an uncomfortable kneeling or sitting position for hours of work with a hand grinder, turn to an edge grinder.

EDCO’s 7-inch Magna-Trap Turbo/Edge Grinder (model TMC-7) has a three-position articulating frame, giving users the ability to work in a right-angle, left-angle or straight position. Its adjustable tubular handlebar provides maximum grinding flexibility from a standing position and allows for complete clearance of any vertical surface.

When renting or buying machines, don’t forget to consider what power option will work best for the jobsite. If electric outlets won’t be available, propane or gas are acceptable alternatives.

Selecting the Proper Tooling

The tooling is an essential part of the operation, and the concrete dictates the bond and grit of the accessories needed to equip a grinder. There are three main considerations for choosing the proper accessories for the job — surface, desired texturing and application.

To evaluate the concrete and ultimately choose the proper tooling, the first step is to determine the age of the concrete. If the concrete is less than 28 days old, it is considered “green” concrete. That fresher concrete can be soft and abrasive, and it eats up the diamond tooling quicker. Therefore, a hard bond is the best option for new concrete.

Any concrete older than four weeks is considered “cured” concrete, which can be soft, medium or hard. There are two primary ways to find out. The first involves taking a core sample and sending it off to be tested, while the second is through a self-administered Mohs hardness test. That test kit includes three scratching tools that indicate different hardness levels.

The model TMC-7 Magna-Trap Turbo/Edge Grinder in action

After determining the hardness of the concrete, you can choose the proper bond for the accessories. Soft concrete requires a hard bond diamond, medium concrete requires a medium bond diamond, and hard concrete requires a soft bond diamond.

Another component of accessories is the grit. Diamond grits are similar to wood sandpaper grit; a lower number represents a coarser grit and a higher number denotes a finer grit. EDCO’s accessories come in 18 grit, 30 grit, 70 grit and 120 grit, with 18 being the coarsest and 120 being the finest.

Grit is a key factor in determining how much scratching is left behind after grinding. Lower grit accessories that are more coarse leave more scratches, which is oftentimes most conducive for the coating to adhere to the concrete effectively. Meanwhile, using higher grit accessories will leave a smoother finish with minimal scratching.

Another factor that dictates the texture that the grinder leaves behind is the type of accessory used. EDCO offers a variety of accessories for several applications that leave different concrete surface profiles (CSP). A CSP gauges how smooth or rough the surface will be, with lower numbers on the one-through-nine scale representing smoother textures and higher numbers indicating rougher finishes.

If a project requires the removal of another coating first, users may need to start with a more aggressive accessory—depending on the original material. However, it is still imperative to consider how much scratching or gouging is desired, if any at all.

For a low CSP, which indicates little to no texture left, the Dyma-Dot accessories are an ideal option. Dyma-Segs and Dyma-Arrows can also achieve a low CSP while removing general or abrasive coatings. Dyma-PCDs can be used for industrial-strength coating removal but will result in a surface with more texture, thus a higher CSP. Magna-Blades accessories leave a smooth surface and should be used to remove flaking paints, industrial buildups, soft thin-set, foam-rubber carpet backing, glues and adhesives.

For the application of installing an epoxy coating on a concrete surface, check the coating manufacturer’s instructions to find the desired surface texture for their product to adhere properly. But, typically, this application calls for a smoother surface.

Should the user remove a preexisting material first, it may be necessary to add a step to ensure the surface is smooth enough for that new coating by grinding the surface further with an accessory that will leave a lower surface profile. Even if another accessory grouping is necessary, the Magna-Trap tooling can be easily rotated quickly by sliding right into the disc.

Dust Prevention

Dust prevention is a vital part of any job where the user is grinding or cutting concrete, because it ensures safety and compliance with the respirable crystalline silica dust standards from the Occupational Health and Safety Administration (OSHA). Not to mention, it eliminates time dedicated to cleaning up any dust left behind.

Grinding and cutting concrete or stone produces extremely small respirable silica dust particles that can cause serious long-term health risks from silicosis, an incurable lung disease that can lead to death. Ensuring that workers are compliant with OSHA’s silica dust standards can truly be a lifesaver.

A standard shop vacuum cannot contain the dust a grinder produces. Instead, use an industry-proven vacuum system such as EDCO’s VAC-200. The VAC-200 features two high-efficiency particulate air (HEPA) filters and a MicroClean filter, which help the vacuum capture 99.97% of silica dust at 0.3 microns efficiency—well within compliance of OSHA’s standards.

The Process

After securing the requisite machines, accessories and dust-prevention methods at the jobsite, the process is ready to begin. Start by clearing and surveying the jobsite to ensure there aren’t any hazardous areas that will damage the equipment or high spots on the surface.

If removing a preexisting coating first, equip the edge grinder with the necessary accessory and grind along vertical surfaces and tight areas to create the perimeter. Then, use the larger turbo grinder to remove the coating in the middle of the working area. Never push the grinder like a lawnmower; instead, move it side to side while working around the area.

The TMC-7 edge grinding

Should the surface require further smoothing, or if starting from a bare concrete floor that needs to be smoothed out, repeat those steps with the Dyma-Dot accessories or another tooling option that leaves a low concrete surface profile.

After the smoothing process is complete using the grinders, the surface is ready for a primer coat. Use a small hand brush to work along the walls and other vertical surfaces before using a large roller with a long handle on the open floor.

Once the primer is set, examine the surface to identify and patch any cracks or pits before moving to the next step. Next, pour epoxy around the perimeter before using a small hand brush to apply epoxy around the edges and in those tight areas. On the open floor, use a squeegee to spread the coating evenly around the surface.

Then throw a copious amount of epoxy flakes around the surface. Epoxy flakes are beneficial because they are durable, easy to maintain, improve traction and create a decorative and abstract granite look.

Seal the epoxy and flakes with a urethane clear coat, using a long-handled roller around the surface. Last, finish the job by spraying or applying a coat of slip-resistant material. Once the transformative process is complete, your garage or shop floor is ready for heavy foot or machinery traffic, along with the everyday rigors of your operation.


Eric Myers, Equipment Development Company

Eric Myers is currently a writer for EDCO and has worked with the company in several roles since June of 2015.