Direct-to-metal (DTM) coatings protect metal substrates from corrosion and serve a dual purpose as a topcoat. Waterborne DTM coatings are suitable for light-duty applications such as interior spaces where condensation may occur or exterior environments with low levels of pollution, and are used as coatings for pipes, tanks, handrails, steel doors, rail cars, etc. When compared with multilayer coatings (primer layer followed by a topcoat layer), there are cost and time advantages in choosing DTM coatings. These coatings are intended to be applied after minimal surface preparation with only one application step, and are designed to provide corrosion protection without the need for active pigments. Waterborne acrylic DTM coatings can provide a high-gloss finish (>80 on a 60° meter) with good appearance and protect the metal substrate from corrosion.
Waterborne coatings provide advantages over solventborne coatings because they are better for worker health and safety, with less impact on the environment. Waterborne coatings are easy to clean, can be thinned with water and use solvents that are lower in odor, toxicity and flammability. Lower-VOC acrylic coatings also dry faster, which allows for faster recoating times. One of the challenges of waterborne coatings in general, however, is that application conditions can affect the appearance and performance of the coatings. Low temperatures and extreme humidity (high or low) must be avoided for optimal application appearance and film formation.