Light Absorption in Liquid Contents and the Color of the Glass
Research by Bradley E Sturgeon, PhD at Monmouth College in Illinois in 2008 showed that different colors of glass allow different levels of UV light into the bottle’s liquid. He used both tungsten light and sunlight. The sunlight contains high amounts of UV by nature. The tungsten much less.
The results show that a clear glass protects the liquid inside from UV exposure 0%. Brown glass filters the largest amount of high energy light. Green and especially blue are inefficient at filtering the higher energy UV light.
Brown bottles filter over 80% of the UV light, allowing for the health of the liquid inside. With essential oils, which degrade quickly with UV or other high energy light, it is critical to use brown glass containers.