Phase II for Epoxy Floor Coating Preparation and Application
Final Acid Etching, Patching Holes and Epoxy Application
The hard part is now completed. You have tested the concrete, cleaned and degreased it, and profiled it with a chemical / acid etch or by diamond grinding.
Final Acid Etching
Just to be safe, here are the summary steps for the acid etch process:
- Properly clean concrete surface by removing all dirt, dust, grease, oils, wax, release agents, or any other contaminants that will interfere with the proper etching and preparation of the concrete surface. Some contaminants such Sealers should be removed by mechanical means (Shot blasting, sanding, grinding or sand blasting).
- Properly mix acid solutions if acid is being used
- Wet-out concrete surface with fresh/potable water (no ponding)
- Apply acid solution uniformly.
- Allow acid time to react: 2-10 minutes.
- Rinse/scrub surface.
- Check profile. Should be between 80 grit – 120 grit open coat AO sand paper.
- Check ph (ideal is 7, 6-9 is acceptable) Neutralize surface if necessary. Rinse and scrub surface.
- 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.
The next steps include patching any holes or cracks before applying the epoxy.
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.
You are now at the final steps, and your hard work during preparation will be rewarded.
Important points are to mix the epoxy in quarter size blocks so the mixture does not harden early. If all the mix is prepared at once, the pot life will be very short.
Careful attention must be paid to floor temperature and surface cleanliness to ensure a smooth and even coating. Colored flakes and non-skid additives are put down at this stage of the application.
When all the preparation steps and the mixing and application steps are followed, you will have a beautiful, durable and chemical resistant floor. And you will be the envy of your neighborhood!