What Is a Polyurethane Coating?
Polyurethane coating, often referred to as “urethane” in the paint industry, is a painting process using a specific type of paint. This coating is known for its glossy finish, imparting a luxurious appearance. Polyurethane resin, noted for its good adhesion to metal surfaces, is a soft resin, making it durable and easy to work with.
Uses of Polyurethane Coatings
Historically, polyurethane coatings were widely used for exterior wall coatings due to their cost-effectiveness compared to other types of paints. However, they have been largely replaced by silicone coatings for exterior walls due to the latter’s higher durability. Nowadays, polyurethane coatings are primarily used for waterproofing applications in areas such as balconies and gutters. Additionally, they are commonly applied to cars, motorcycles, tableware, and furniture, offering moisture resistance superior to oil or lacquer coatings, making them especially popular for furniture applications.
Types of Polyurethane Coatings
Polyurethane coatings are categorized into water-based and oil-based types, each with distinct characteristics:
- Water-based Paints: Diluted with water, these paints are cost-effective and environmentally friendly, emitting less odor. However, they tend to be less durable and their glossiness can fade more quickly compared to oil-based paints.
- Oil-based Paints: Diluted with organic solvents like thinner or benzene, oil-based paints offer greater durability but are more expensive and have a stronger odor than water-based paints.
Both waterborne and oil-based paints are further classified into one-component and two-component types, based on the need for mixing with a hardener before use. One-component paints do not require a hardener, while two-component paints, though more labor-intensive, provide enhanced durability due to the chemical reaction between the hardener and the main paint.