Coatings appropriate for industrial interior overcoating fall into four classifications, said Kline. For acid or alkali environments, epoxies and urethanes are the choice. For more neutral environments, there are alkyd paints and water-based acrylic materials. These are less expensive and easy to apply. Let's say your factory interior generates acid or alkaline fumes, and your coating needs to be chemically resistant.
Urethanes weather better, since epoxies chalk with exposure to sunlight.
But indoors, the less-expensive epoxy might be a good choice, said Steven Harrison, marketing director for Carboline Co. in St. Louis. The preparation of epoxies is simpler, Harrison said. In addition, epoxies are more tolerant of poor surfaces, Harrison said. There are still good reasons to use urethanes, though. Urethanes dry considerably faster than epoxies, permitting a job involving several coats to be done in less time.