Colloquially, people use the term urethane to refer to a type of varnish, while the term Varathane refers to a brand of varnishes, sealers and similar products. Technically, urethane is not the correct term for the wood-sealing product, even though it is commonly used. Urethane is another name for ethyl carbamate, which is a chemical used in industrial applications. The correct term for the sealant is polyurethane.
Polyurethanes are produced by a variety of companies, and they come in a variety of styles and formulations that are suited for different purposes. For example, some sealants have a matte finish, while others have a high-gloss finish. Some polyurethanes are well suited for commercial applications and high-traffic areas, while others are likely to wear out after constant use. Some polyurethanes are oil-based, while others are water-based. The water-based formulations dry quicker than the oil-based products do, but they are more expensive and may not last as long. However, cleanup is much easier with the water-based products, which are water soluble; mineral spirits or turpentine is necessary for cleaning up after using the oil-based products.
Most polyurethanes serve as the final coat for wooden items. Because polyurethane is often clear, it is important to ensure the surface is completely clean before application. Do not shake these products before use, as this may cause bubbles to form. Instead, stir the paint to ensure uniform consistency.