Why Are Beer Bottles Brown?

Beer bottles are often brown to protect the contents from light exposure, which can lead to unwanted changes in flavor. Light, especially ultraviolet (UV) light, can trigger a chemical reaction in beer. This reaction, often referred to as “skunking,” results in an unpleasant smell and taste. Brown glass helps block harmful UV rays, preserving the beer’s intended flavor and aroma.

Brown is especially effective because it absorbs more UV light than other colors, such as clear or green glass. Although green and clear bottles are still used for aesthetic or traditional reasons, they offer less protection, which is why brown remains the preferred choice for many brewers.

The use of brown bottles isn’t new. Brewers learned long ago that beer stored in darker glass held its quality better than beer in lighter bottles. That practical insight has since been confirmed by science, reinforcing the continued use of brown glass.

Brown glass offers excellent protection, but even it can’t block all light. For best results, beer should still be stored away from direct sunlight to maintain its freshness. And though it’s commonly called brown, the glass is technically amber—a color prized not only for shielding beer, but also for preserving prehistoric life in fossilized tree resin for millions of years.