Aliphatic polyurethane is a UV stable topcoat that resists yellowing in sunlight, unlike aromatic polyurethane which ambers quickly when exposed to UV light.
Understanding Aliphatic Polyurethane
Aliphatic polyurethane is a type of urethane topcoat built on a chemical backbone that resists breaking down when hit by UV light. It is commonly applied as the final clear or pigmented layer over an epoxy or polyaspartic base coat to add abrasion resistance, chemical resistance, and long term color stability.
Aliphatic vs. Aromatic Polyurethane
The key difference between aliphatic and aromatic polyurethane comes down to how each reacts to sunlight. Aromatic polyurethane is cheaper to produce but yellows and chalks quickly when exposed to UV rays, sometimes within weeks outdoors. Aliphatic polyurethane costs more but holds its color and gloss for years, which is why it is the standard choice for any floor that sees natural light.
Where Each One Is Used
Aromatic polyurethane still has a place as a primer or base layer in systems where it will be fully covered by a UV stable topcoat, since its lower cost and strong bond make it useful where appearance does not matter. Aliphatic polyurethane is used wherever the final look matters, including garage floors, retail stores, showrooms, and any coating system with outdoor exposure like patios or pool decks.
Why the Distinction Matters
Some budget flooring systems get sold with an aromatic topcoat labeled simply as “polyurethane” without clarifying which type. The homeowner or business owner does not notice a problem until the floor starts to amber and lose its shine, often within the first year. Confirming aliphatic chemistry on the technical data sheet before installation avoids this callback.
Also Called
Aliphatic Urethane, UV Stable Polyurethane Topcoat
