Sweating concrete floors are an issue in areas where high humidity occurs or where there is little air flow. Sweating floors produce moisture on their surfaces, which can be difficult to get rid of and damaging to the room. Too much moisture on the floor can develop mold problems or damage surrounding materials. There are several methods you can use to minimize floor sweating problems, including using different types of sealers.
Paint sealers are useful because you can use them on a concrete floor that has already been installed and aged. While you still have to carefully clean the floor in preparation, you do not need to apply the sealer when laying the concrete or immediately afterward. This makes it easier to address a sweating problem that has only just begun or was only recently noticed. Sealants work much like paint: you apply them with a roller or brush and let them dry. They keep moisture from passing all the way up through the concrete and minimize sweating problems.
Curing compounds are a different type of sealer that must be applied when the concrete is still curing -- in other words, when it has not fully dried. Sweating problems may depend on the type of concrete being used, including how porous and consistent it is. Curing compounds coat the surface of the concrete and help it solidify properly. A well-cured concrete surface is more dense and has fewer sweating problems than poorly laid concrete. On the downside, you must apply the curing compound when installing the concrete.
Vapor barriers are similar sealants to curing compounds in that they must be installed at the time the concrete is being laid (or before that, actually), but they are not liquid sealers. Instead, a vapor barrier is a sealing layer of plastic that is placed below the concrete. This has both advantages and disadvantages. It stops moisture from rising up from the ground and soaking into the concrete, and continuing the problem. But on the downside, it also makes it more difficult for air to pass through the concrete, dispersing its moisture. Semi-permeable vapor barriers work the best.