To refinish a concrete floor, remove the existing sealer using a chemical-based stripper, and use a hooded floor grinder to remove the existing color. Then, clean the concrete floor, and apply the desired concrete stain or dye. Finally, apply sealer on the floor.
To remove the existing sealer on the concrete floor, apply masonry or concrete stripper over it using an airless sprayer or a paint brush or roller. Leave the stripper on the floor for about six to eight hours. When the stripper begins to peel and forms bubbles, scrape it out using a metal brush or scraper, and discard as hazardous waste. Hose water on the floor, mop it, collect the stripper material, and dispose.
To remove the existing floor color, run a rented hooded floor grinder over it until the stain is removed completely. If grinding the concrete floor, removing the seal separately using a stripper is not required.
Use a dilute trisodium phosphate solution to remove stains and grease from the floor, and rinse with fresh water. Prepare the concrete dye or acid stain as per the instructions given, spray it on the floor using a garden sprayer, and roll it with a roller to distribute the color uniformly. Allow the stain or dye to dry overnight.
Apply the sealer as per the instructions of the manufacturer, using a paint roller, brush, sprayer or trowel. If desired, paint the floor, and apply a polyurethane-based floor finish two times.