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This concrete / epoxy coating application guide was developed to insure the best possible results are achieved when applying U.S. Industrial Coatings floor coating products.
Applying epoxy over concrete is not difficult, but there is more to it than simply painting a garage floor.
This guide will take you through each step; from deciding which epoxy coating product will best provide the desired results, to measuring the area and calculating how much epoxy (and other products) you will need, to concrete surface preparation, epoxy application, clean up, and floor maintenance. We've also included a troubleshooting section in case you run into any problems, and a glossary of epoxy / concrete related terms.
There are many different grades and formulations of epoxy floor coatings on the market. Much of the decision of which to use is based on what type of material (or "substrate") you plan to coat. This guide is specific to applying epoxy on a horizontal concrete substrate. (Much of the information also applies to application on vertical or inclined concrete surfaces, but there are differences -- if you need to coat walls, columns, supports or other vertical surfaces, contact your U.S. Industrial Coatings representative for additional product and application information. U.S. Industrial Coatings also carries a complete line of epoxy and urethane coatings for application on other substrates such as wood, metals and previously coated surfaces).
After taking into account what type of substrate you plan to coat, the next consideration is the environment of the area to be coated. Whether you are a home-owner and want to "paint your garage floor" (with epoxy), or are coating a large commercial automotive service area, there is a U.S. Industrial Coatings product to fit your needs.
High traffic, high impact areas, floors which must stand up to extreme temperatures, acid or other chemical resistance properties or simply desired color and finish texture should also taken into account.
100% Solids epoxy coatings are typically used in commercial and industrial settings, and although they do provide the highest level of durability and resistance, they are also more costly and more difficult to apply than epoxy coating products which have a lower percentage of epoxy solids.
There are special formulations for extreme temperatures, (such as refrigeration or freezer floors), coatings for high-impact floors such as industrial or manufacturing environments, special formulations for food handling areas, automotive service areas, and acid / chemical handling areas. U.S. Industrial Coatings offers a complete line of residential, commercial and industrial epoxy and urethane coating products.
U.S. Industrial Coatings recommends using our solvent based 65% Solids "two part" ("A-B" mix) for residential garage floors.
To calculate how much to order, you will need to measure the length and width of the area. Multiplying the length times the width will give you the size of the area in square feet.
A traditional 2-car garage is approximately 24' x 24', or 576 square feet. When calculating how much epoxy you will need, always round your figures up, it is better to have a small amount left over than to run short while applying the coating.
Once you have calculated the area, you will need to calculate how many coats of epoxy need to be applied to achive the desired thickness, (which is measured in "millimeters" and usually referred to as "mils").
U.S. Industrial Coatings epoxy floor coating (which is sometimes referred to as "epoxy garage floor paint"), is sold in "kits". Each kit consists of two 1-gallon cans, ("Part A" and "Part B"). Each gallon of U.S. Industrial Coatings 65% Solids Epoxy will cover approximately 200' sq. at approx. 5 mils.
In our example of the 24x24 garage, we calculated the area of the floor to be (approximately) 600 square feet. Since we recommend applying at least 9-10 mils, which requires 2 coats, you would need a total of 6 gallons, or "3 kits".
U.S. Industrial Coatings products are formulated to meet the highest standards. To perform as expected, (and we can not stress this enough), proper surface preparation, ("prep"), is the key to obtaining the best results when applying epoxy coating over concrete.
Concrete is a mix of Portland cement, sand, stones, ("aggregate"), and water. Concrete floors, in different situations, require different preparation before epoxy coating is applied.
Concrete may be a new pour, (concrete which was recently poured), or it may be an older concrete floor and be dirty, stained, cracked or crumbling. Another situation to be considered is apply epoxy coating or previously coated or painted concrete floors.
Is the concrete that you want to epoxy coat a new pour?
If applying epoxy coating over a new pour, it is suggested that you wait a minimum of 30 days before coating. For concrete over 4" or 5" thick it is suggested that you allow even longer for concrete to cure. To test is concrete is fully cured, (or if there is still moisture present), tape a 4' x 4' sheet of clear plastic in middle of floor and leave in place for 24 hours. If not fully cured, moisture will be trapped beneath plastic sheeting and surface of concrete will appear dark or wet in that area. Remove plastic and allow to fully cure. Repeat test once every 3-5 days until there is no noticeable difference in concrete appearance beneath and around plastic sheet. NOTE: if several weeks go by and moisture is still present it may be due to hydrostatic pressure.
If the concrete floor you want coat with U.S. Industrial Coatings is in fairly good condition, (no heavy oil staining, no crumbling and concrete was not previously coated or painted), you will still want to thoroughly clean and etch the surface to insure a good bond between the concrete substrate and the epoxy floor coating.
The surface of freshly cured concrete may sometimes have a milky-white residue. This is called concrete efflorescence, and must be removed prior to epoxy coating application.
Efflorescence is the deposit of salts, (calcium, sodium, potassium, magnesium, chlorides and sulfates), which rise to the surface of concrete. Heavy accumulation of the efflorescence can be removed with a stiff brush, residual salts can be removed by washing with clear water. On older concrete floors where efflorescence salts have formed into calcium carbonate or magnesium carbonate deposits, removal with a chemical cleaner or acid may be necessary.
Begin by sweeping and/or blowing away any heavy accumulations of dirt or loose debris. Be sure to blow or sweep away any leaves, dirt, debris from surounding area --- anything that could blow in through garage door, (pressure washer can be used for this if you don't have a blower).
Next using a pressure washer, thoroughly wash every inch of surface to be coated. (If you do not own a pressure washer, they are available at most tool rental centers. We suggest using a a pressure washer with between 2500 and 3500psi). Be careful! You may not realize how powerful the force of water is, but a high powered pressure washer can actually cut into concrete.
Note any areas where water appears to bead or is repelled, there is a possibility that wax, grease, motor oil, transmission fluid or other oily residue exists in the substrate. If this is the case, you will want to use TSP, (Tri-sodium-phosphate), or other de-greaser and scrub area until water will penetrate the surface. Wash again with pressure washer after using any de-greasing agents or cleaners.
After pressure washing, examine the surface closely, you may find cracks, low or high spots, or other defects in the surface which should be repaired to achieve the best finished appearance.
Epoxy coating may fill and bond very fine hairline cracks, but larger cracks require use of crack filler, and for extremely wide, jagged and / or deep cracks, you may need to grind out concrete, and patch using epoxy / concrete patching kit.
If there are low spots in the concrete floor, use our epoxy patching compound and trowel mix onto surface to level low areas.
Once entire floor has been pressure washed, and de-greased (if needed), the entire surface must be etched to insure a proper bind between epoxy floor coating and underlying concrete floor.
To etch concrete, mix equal parts muriatic acid and water and disperse over surface of concrete floor. Allow acid to sit on floor for approximately 20 minutes, then rinse thoroughly with clear, clean water until all remaining acid has been washed away.
Once a concrete floor has been properly prepared, (cleaned, degreased and etched), there are two factors that must be taken into account at the time the epoxy coating is applied.
The two factors, temperature and humidity, will affect the outcome of the application.
In general, epoxy concrete coatings should applied when temperature is in the 50 to 80 degree range.
Humidity should be no higher than 80 percent, (the lower the humidity the better).
Be aware of temperature or humidity level changes that will occur during the course of the application and drying time. Although you may start an application at 7:00am and the temperature is at 60 degrees --- by noon the temperature can, and most likely will rise or fall. In many cases, afternoon temperatures will rise even higher than noon-time temperature. You must be sure that the temperature will remain within recommended levels during epoxy coating application and drying times on large commercial jobs or when applying 2nd coat to smaller jobs.
If you are sure that the temperature and humidity are in the recommended range, the next step is to mix the epoxy coating product.
As mentioned, we are using our 65% Solids Epoxy for coating a garage floor as the example job in this application guide. This product is mixed in equal parts, (mix equal amounts of "Part A" with equal amount of "Part B"). Be sure to only mix as much as you can apply in a 30-60 minute period.
To mix 2-gallons of epoxy, pour "Part A" and "Part B" into a clean 5-gallon plastic bucket. Mix using a Jiffy Mixer or mixing paddle on a low speed 1/2" drill. Start with mixer at bottom of bucket --- do not lift mixer / paddle in and out epoxy as this will induct air into the mixture. Mix thoroughly for 3 to 3 1/2 minutes, (use a timer -- it is very important that you do not mix for longer or shorter periods of time).
You will want to begin at the furthest point from the door(s) using a paintbrush and cutting in some edges, inside corners, doorway openings and other areas where epoxy can not be easily applied with a roller. Do not cut in too far ahead to prevent drying. After cutting in, begin to roll out floor using a paint roller with a solvent resistant phenolic core shed proof epoxy roller cover, (covers are available from U.S. Industrial Coatings).
You will "paint your way out (of the garage), so that you do not need to walk on wet epoxy or drag equipment or materials across wet areas of floor. Continue to cut-in and roll-out areas, always applying wet epoxy to wet epoxy until entire floor area has been coated with epoxy.
Each U.S. Industrial Coatings floor-epoxy coating product has specific properties including drying or "curing" times. As with other areas of the application guide, we will use the example of applying our 65% solids fast-set epoxy coating over a concrete garage floor.
The first coat of epoxy should be dry to the touch in 1 to 3 hours. There is no need to touch floor unless you plan to add additional coats of epoxy. To test, press thumb into epoxy coating (on last area applied) after waiting 2 to 3 hours. If no fingerprints are left in epoxy, you may begin applying additional coat.
Once all coats have been applied, allow 16 to 24 hours before even light foot traffic is allowed across floor. The floor should be fully cured anywhere from 3 to 7 days, (depending on temperature, humidity, total thickness of application and proper ventilation.