Ask Mr. Wizard

Bottle Colors

TroubleShooting

Jake Ocque • Buffalo, New York asks,
Q

In the December 2007 issue of BYO, you gave an answer about light skunking a beer. You stated that it was UV light that was damaging the beer. I don’t see how this is possible. It must be visible light if any light is destroying a beer at all. For example, our eyes cannot see UV light, hence the name “visible light.” So, why then would the visible color of a bottle determine its ability to transmit or reflect UV light. In fact, glass itself actually absorbs most UV light that reaches it no matter what the visible color of the glass; this depends on the quality of the glass, for example the amount of silica and quartz in the glass. A brown bottle is brown because it absorbs visible “brown” light. A green bottle is green because it absorbs “green” light and so forth. So then if UV light does in fact “skunk” a beer, then the color of the glass would have no effect.

A
  Thanks for the great comment with respect to my answer about hops and skunkiness, Jake. I have spent several hours reading and have gained a new appreciation for glass and the
Response by Ashton Lewis.