Painting a concrete or cement floor requires more preparation than painting wooden walls or the like. If a concrete floor isn't properly cleaned and prepared, the paint will begin to chip almost immediately. This will make any future attempts to repaint the floor even more difficult.
Before applying any floor paints, it's important to completely clean a cement or concrete floor. It's recommended to use a high-power pressure washer to do this, as that will have the highest chance of cleaning the floor thoroughly. It's a very messy process, though, and may not always be available depending on the environment. In those cases, the only choice may be to manually clean the floor and remove any old paint with a wire brush and scraper.
The next step is to seal and prime the cement floor. If sealing is not done, moisture can creep through the floor and discolor or remove any floor paints you might use. This process is especially important in basements, where moisture is common. Priming the floor allows the floor paints to properly adhere to it. Don't be cheap when shopping for a concrete sealer or you may come to regret it.
Once sealed and primed, you can begin to apply the concrete floor paint, one coat at a time. It's important that you choose the right type of paint for the job. Some paints are general masonry paints, while others are specifically designed for use on floors.
If these cement painting techniques don't work, epoxy floor paint is also an option. Epoxy floor paint will leave the floor with a glossy sheen that resists oil, grease and other things that could ruin normal paint. Many of the same warnings apply for epoxy paint – the floor cannot have moisture coming through it, or the epoxy won't hold.
There are two common types of epoxy floor paint: solvent-based and water-based. Both types involve mixing together two chemical parts before applying them to the surface. The main difference is that solvent-based epoxy produces noxious fumes, so one must take precautions to avoid inhaling them. Water-based epoxy is the safer choice, but most professionals prefer solvent-based epoxy.