Paint a Concrete Floor
Project Scenario
Jim wants to paint the floor in his manufacturing work shop. There is impact from dropped tools, but no forklift or heavy equipment use.
Red Alert
A moisture test is MANDATORY. Perform a moisture test (ASTM3359)
- Use 4 mil visqueen (2 feet x 2 feet)
- Duct tape all four sides to floor.
- Wait 24 hours and look for condensation under the plastic.
- If wet, do not paint because of hydrostatic pressure.
Preparation
- Complete a moisture test (above).
- Remove dirt and grease by scrubbing with hot water and a strong degreaser or detergent. Rinse thoroughly. The wet surface, when clean, should be one continuous sheet of water with no beading in any areas.
- Rough up smooth floor to achieve the look of 100 grit sandpaper using one of the following methods:
- Acid etch if there is a drain (May require multiple applications)
- Blast-trac (Do not overdue profile or extra coats may be required)
- Grind and Go.
- All dust must be removed by vacuum or mop. Let dry thoroughly.
- Clean cracks out to remove loose concrete, obtain and apply a paintable concrete patch.
- Fill cracks with an epoxy crack filler designed to be painted.
- Check walls for moisture before coating. Determine and correct the source of moisture before painting.
Caution! Things to consider
- For anit-slip, non-skid coating, add sand to the film, by hand broadcast, during the first primer coat. Create test area to determine how much sand to add.
- If floor is exposed to sunlight, be aware that epoxy coatings yellow over time. Polyurethane coatings are more resistant to UV exposure.
- Do not let acid solutions dry. They will be very hard to remove.
- Do a test patch to check for adhesion.
- Before painting, extinguish any open flames such as pilot lights on furnaces and gas water heaters.
- Fill expansion joins after the floor is coated. Top coatings will not flex over the joint filler. Cracking and flaking of the paint will occur.
- Epoxies will chalk out in the presence of sunlight. A 2 part polyurethane topcoat will keep the floor color and gloss retention.
- No floor coating is indestructible. In areas subject to abuse, floor mats are a good idea to protect the paint from being chipped when items are dropped.
- Do not use alkyd paints if there are moisture problems. Alkyd paints will peel up when lime is present.
