Epoxy Floor Coating System for Garage, Basement, and Cement

FLOOR PREPARATION PROCEDURES

Epoxy-Coat is a do-it-yourself industrial grade epoxy floor coating kit designed for optimum performance. One major variable our kit cannot control is floor preparation. There are many ways one can prepare concrete floor.

YOU MUST:
1. REMOVE CONTAMINANTS
2. REMOVE SEALERS OR WAXES
3. REMOVE ANY POORLY BONDING COATINGS.
4. CREATE A PROFILE (SIMILAR TO A 100 GRIT SAND PAPER) SO THE COATING CAN PERMEATE INTO THE CONCRETE AND CREATE A PROPER MECHANICAL BOND.

NEVER COAT OVER A SHINY CONCRETE SURFACE OR A CONTAMINATED SURFACE.


Our recommendation for surface preparation is specified below in the order of recommendation from first to last:

1. SHOTBLAST, SCARIFY OR DIAMOND GRIND CONCRETE SURFACES (mechanical surface preparation means).
2. MURIATIC ACID ETCH (hydrochloric acid)

Acid etching is the process of applying an acid solution to a concrete surface, allowing the acid to react with and 'etch' the concrete.

Acid etching of concrete is an acceptable, but less popular method for commercial concrete surface preparation than SHOT BLASTING. However, because shot blasting requires special equipment and trained professionals (generally special contractors) acid etching is perhaps the most “serious” surface preparation method available to do-it-yourselfers’. For such people, as well as professional flooring contractors (if the engineer in charge allows acid etching) the following guidelines are suggested (but not in any way endorsed, recommended or approved – follow at your own risk and responsibility.


NOTES SECTION

NOTE: : Acid etching will not remove sealers or concrete surfaces. They must be removed mechanically – i.e. shotblasting, sandblasting, or scarifying. Sealers that soak into the concrete might not be removed at all.

NOTE: Acid etching is often used by individuals for surface preparation of home shops, garages, basements, etc.

NOTE: If the concrete is contaminated with oils and grease, the first step is to clean the surface with an alkali detergent cleaner and commercial degreaser (optimal removal is to us the detergent in combination with a steam cleaner). See DEGREASING section on our Surface Preparation Page.

THE TYPES OF ACIDS FROM 1ST MOST RECOMMENDED TO LAST IS AS FOLLOWS:

1: HYDROCHLORIC (MURIATIC) ACID

Usually sold in 31.5% solutions. Dilute to 4 TO 1 and apply from 250-500 sf.

2: PHOSPHORIC ACID

Used when the strong acid fumes cannot be tolerated or around acid vulnerable metals such as carbon or galvanized steel. In these situations a solution of 20% - 40% Phosphoric Acid.

The following is a guide to procedures required to properly prepare concrete for the application of thin film coating systems by acid etching:

CAUTION: Acid etching requires the use of strong chemicals. Used improperly, these chemicals can result in severe injury. When handling harmful chemicals, always wear protective clothing and protective eye wear/ face shield, read instructions carefully.

Always add acid to water. Never add water to acid!

Protect surfaces not to be etched from chemical vapors, splash and spill.
Dispose of all residual material according to local and national regulations.
Scope: Acid Etching of Concrete for the Application of Coating Systems

      1. Properly clean concrete surface.
      2. Properly mix acid solutions.
      3. Wet-out concrete surface with fresh / potable water. (No Ponding)
      4. Apply acid solution uniformly.
      5. Allow acid time to react – 2 – 10 minutes.
      6. Rinse / scrub surface.
      7. Check profile. Should be between 80 grit – 120 grit open-coat AO sand paper.
      8. Check ph. (Ideal ph is 7, 6 – 9 is acceptable). Neutralize surface if necessary. Rinse and scrub surface.
      9. Dry total surface thoroughly before applying the coating system.

For the best performance from a coating system, concrete must be clean and have a uniform open / porous surface before application. The surface must be etched until this is achieved. More than one etch may be required.

  1. Properly clean concrete surface. Remove all dirt, dust, grease, oils, wax, release agents, or any other contaminants that will interfere with the acid etching and preparation of the concrete surface. Mechanical cleaning with brushes by hand or machine will be required for cleaners to work properly. Some contaminants such Sealers can be removed by mechanical means (Shot blasting, sanding, grinding or sand blasting).
  2. Properly mix acid solution. Acids that can be used to etch the concrete are, muriatic, Sulfamic, phosphoric, or citric. The most commonly used are muriatic (hydrochloric) and phosphoric acids. Use only plastic or acid resistant containers for mixing and applying acid. Acids concentrations can vary. To determine the strength and concentration to use to etch the concrete, test with a very dilute solution then add acid to container until strong bubbling action is noted in the test.
  3. Wet-out the concrete with clean fresh, potable water so the concrete is uniformly wet, without any standing or ponding water. The concrete must stay wet until the acid solution is applied.
  4. Apply acid solution uniformly. The use of a plastic watering can will enable you to make a sure fresh acid is applied evenly over the surface to be etched. (Do not take a bucket of acid and dump it over the floor and spread it around with a broom. It will roll over the area and will neutralize as it spreads giving an uneven etch to the surface of the concrete.) Applied properly to a clean surface, the acid will begin to bubble indicating that the acid is reacting with the concrete. (If the acid fails to bubble on all parts of the floor it means that the surface wasn’t clean thoroughly or a sealer is still on the concrete. The area must be cleaned and etched again.) Use a stiff bristle brush to scrub the acid into the surface and remove the layer of concrete to create the profile needed to apply the coating system.
  5. Allow acid time to react: 2-10 minutes. Do not allow any areas of the etched concrete to dry out during this time.
  6. Rinse/scrub the surface. When the bubbling of the acid on the concrete surface slows noticeably, flush the concrete thoroughly with plenty of water while scrubbing the surface with a stiff bristle broom to remove the powdery residue from the pores of the concrete. Collect and dispose of the liquids according to local and national regulations. Further neutralize the acid by sprinkling baking soda on the wet floor area. After the floor is dry any powdery residue that remains on the concrete must be removed before applying the coating system.
  7. Check the profile; it should be between 80 – 120 grit sand paper. The concrete must have a uniform open/porous surface before application of the coating system. The surface must be etched until this is achieved. More than one etch may be required.
  8. Check the pH (ideal pH is 7, 6-9 is acceptable). Neutralize surface if necessary. Rinse/scrub surface. If the pH is below 6 residual acids are in the concrete surface and must be neutralized. One cup of household ammonia per gal of fresh potable water will usually neutralize the concrete in one application (or sprinkle baking soda). Apply solution uniformly over the surface. Let stand for 10 minutes before flushing and scrubbing with fresh potable water. Re-check the pH and repeat if pH is below 6.
  9. Dry total surface thoroughly before applying the coating system. Check moisture content with acceptable moisture meter. In the absence of acceptable moisture meter follow ASTM Test Method D 4263-83: Standard Test for Indicating Moisture in Concrete by the Plastic Sheet Method. Tape sheet of 4-mil thick polyethylene plastic, at least 18 inch by 18 inch square onto the concrete with 2 inch wide duct tape. Perform at least one test for each 500 sq. ft. of concrete. Allow sheets to remain in place for at least 16 hours before removing and testing back of sheet and concrete surface for moisture. Drying the concrete can be accelerated by heat and the use of fans to blow the air across the surface to the concrete.

Remember: For the best performance from a coating system, concrete must be clean and have a uniform open/porous surface before application. The surface must be etched until this is achieved. More than one etch may be required.

ONE: Initial Comments:

Surface preparation is, or should be, a significant portion of any epoxy coating project. Each surface and environment is different and unique. It is important to note that certain chemicals and materials added to the concrete before, during or after it is poured can cause a coating job to fail no matter what level of surface preparation is used. Suspects include special concrete curing compounds, chemical hardeners, bond/form release agents (bond breakers), and admixtures used to reduce/improve air entrainment, cement workability, gas forming, accelerated curing, etc. It is nearly impossible to know ahead of time how much preparation is necessary. A minimalist will simply brush or sweep the surface (perhaps degrease a spot or two), apply the coating and hope for the best. Often this is all a homeowner can do. Fortunately, they often get away with this alone.

TWO: Surface Preparation of Concrete

Surface Problems Associated with Concrete – Comments
Grease and oils can create serious adhesion problems for coatings. Degreasing and washing may appear to remove the grease or oil, but in badly saturated situations residual oils/greases seem to remain and may cause a coating failure in the future. While not definitive test, pouring a glass of water on the concrete and watching what happens can provide a valuable clue to coating adhesion. If the water quickly and evenly soaks into the concrete the surface preparation may be adequate at that point. Moisture either in the concrete, and/or migrating through the concrete can cause coating failure as well. Some epoxies will handle a wet or damp surface better than others. Note that crystals forming on the surface due to water migrating through the mineral rich cement can create forces of up to 1,500 pounds of pressure as they grow in size. Few coatings can withstand such “anti-bond” forces.
Irregular surfaces on the floor will show through the epoxy and may be more noticeable after the epoxy is applied. Fill or patch any irregular surfaces on the floor before beginning. You can mix sand into a small amount of epoxy to form a slurry (the sand will decrease the amount of epoxy needed) to fill voids and large cracks above 3/16”. With cracks 3/16” or smaller you should use a flexible acrylic adhesive caulk which is paintable. Do not fill in or paint over expansion joins in the floor. The epoxy will crack, split and lift off when there is movement along the expansion seam.

During the coating process, if the floor is subject to heating and cooling cycles, air bubbles (that often form tiny craters in the epoxy) can sometimes be a problem. As the concrete heats up in the sunlight, the air in the void spaces of the concrete expands and forms a bubble that gets “stuck” in the thickening epoxy. If this is a potential scenario for you, apply the epoxy when the air/concrete is cooling off rather than heating up. When the temperature is falling, the air contracts and will literally pull the epoxy into the concrete void spaces. After the epoxy has cured, the heating and cooling cycles are not a problem. If bubbling does occur during coating you can blow the surface with a leaf blower to “pop” the bubbles. This should be done as necessary for up to 90 minutes after coating to reduce this problem during the curing process.


Is your garage or basement suitable for epoxy coating?

TEST: Put a rubber mat on the floor or tape down a 3 by 3 ft. (or so) sheet of plastic. If water collects between it and the floor there has a moisture problem and any floor paint will probably “pop off”.

TEST: Pour water on the cement. It should soak into the cement in a reasonable time. If it beads up or just sits there for a long time, the concrete has been sealed or is grease or oil contaminated. Could cause problems.

TEST: Try painting a test area with ‘regular' oil based enamel. If it stays down for several months, then it is likely that an epoxy floor will also bond with satisfactory results.

DISCLAIMER: Determining the suitability of coating the floor and the amount and nature of surface preparation required is the responsibility of the end user or customer and not the supplier of the coating product. The above information is not a recommendation by rather general information of a non-specific nature.