Brown glass milk bottles have been occasionally used in the milk industry, especially for the delivery of buttermilk. With this product they have apparently been employed for two very different reasons. Some dealers have selected them because the color eliminates the error of delivering buttermilk for sweet milk. Others have used brown bottles because the color prevents the detection of "wheying off" without a rather careful examination; their use for this purpose should of course give way to an improvement in the quality of the product.
Hammer, B. W. and Cordes, W. A.
"A study of brown glass milk bottles with special reference to their use in preventing abnormal flavors due to light,"
Research Bulletin (Iowa Agriculture and Home Economics Experiment Station): Vol. 5
, Article 1.
Available at: https://lib.dr.iastate.edu/researchbulletin/vol5/iss64/1