The beer bottle is a strong, simple shape which withstands the pressure of fermentation and keeps the contents fresh. Stoneware bottles were common in the 18th and early 19th century. They were slowly replaced by stubby brown glass that was ideal for heavier, less carbonated, ales and porters. But the taste for bottle conditioned beer led to the design of a thick and robust ‘Export’ design which was popular throughout the 19th and early 20th century. The thinner modern bottle is made from brown glass which protects the contents from UV light and prevents spoilage.