Concrete, by itself, is rarely beautiful. Making it something other than a shadowy expanse of gray is up to you. The first thing to realize before you start painting concrete, however, is that not all concrete is created equal. Some have a smooth, rigid surface; in other cases, older concrete may corrode and be porous.
Therefore, traditional paint is sometimes the wrong coating for concrete. Concrete-specific stains have filled a niche in the paint industry, even as they penetrate and fill niches in the surface they were designed to cover.
A man smoothing a concrete floor.
However, this pervasive power is a mixed blessing. Unlike concrete paint, a concrete stain lasts forever. Some varieties even form a chemical bond with the concrete itself. Therefore, the decision on the color to stain the concrete surface must be final.
If you decide to paint concrete, you will have the opposite problem: a tendency for the paint to separate from its surface in a short period of time, especially in high-traffic areas. Concrete painting or dyeing experts recommend that paint not be applied until the surface has at least a week – and some say up to 28 days – to dry and cure. Curing compounds were developed to speed up the setting and drying processes. The problem is that these compounds often prevent the paint from adhering properly.
Ink and a brush.
One solution to this is acid etching. After a surface has been cleaned of dust and grease (with a washing machine if necessary) and washed with a cleaning solution, a dilute solution of muriatic, phosphoric or sulfamic acid is applied, usually with a mop or spray unit to avoid skin contact. This solution will produce a rough surface that is more receptive to paint or stains.
A high pressure washer can be used to clean concrete.
Moisture is the main enemy of painted concrete floors. If seepage areas are not treated prior to paint application, water will collect under the paint and cause bubbles. Applying a sealant is the most direct way to respond to this problem. Once this is done, certain types of paint will “breathe” to allow the moisture to evaporate.
There are literally dozens of types of paints and stains that can be used to paint concrete, from bright colors to earth-toned stains that give concrete a natural look. Epoxy paint is another viable option.
It is generally recommended that several coats of paint be applied in thin coats to ensure uneven areas are properly covered. In other words, painting concrete (or dyeing) is a lot of work. But the alternative is gray.