Okay, the Regimental Brewmeister is a little uptight about bottles. First off, the bottles I use, while definitely anachronistic to the 18th Century, are of a design that came into vogue during the last half of the 19th Century so they are historic (just the wrong era…). But more important than that they are expensive and hard to find. I import my bottles from Germany.
“Flip-top” bottles were invented in 1875 by Nicolai Fritzner of the Schwelmer Brewery in Westphalia (Germany). Fritzner invented the bottles to solve the problem of making carbonated beer bottles with their high interior pressure easy to transport. Corks lacked the resistance to being dislodged by gas pressure so, Fitzner devised a means of clipping the cap to the bottle to hold the cap down. This design quickly became the main bottle-top for beer bottles worldwide and is still popular in Europe, In America, we use the much cheaper “Crown Cap”, which was invented by the American William Painter in 1892. The downside to “Crown Caps” is that they are single use (often also for the bottles), whereas, flip-top bottles are reusable. They just look cool. But as I said before, they are hard to get.
While we are on the subject of bottles, perhaps you’ve noticed that “good” beer always comes in either dark glass or opaque bottles. This is because when hops in beer are exposed to ultraviolet light (ie sunlight), a photooxidation reaction takes place, creating the compound 3-methyl-2-butene-1-thiol which gives beer a “skunky” smell and off putting flavor. Not wanting to disappoint or lose customers, beer manufacturers have long taken efforts to prevent this from happening. This is why we use tinted glass bottles to prevent the UV rays from having a large impact on the liquid inside. And the color of that tint matters. Dark brown bottles block more UV light than other bottles, and therefore, are the most popular ones for bottlers to use. Green bottles are notably less effective and clear bottles provide no protection at all.
That said, my brown bottles are again an anachronism. Most 18th Century glass was green. Most early glassworks were established near sandy beaches because sand is the main ingredient in glass. One of the metallic compounds almost always found in sand is iron oxide in the form of ferrous iron. In normal concentrations, iron oxide gives otherwise clear glass a bluish-green tint. In higher concentrations, it gives the glass a yellowish-green or even dark green tint. Glass left untreated, or “natural” glass, therefore, usually ends up with a greenish tint. To get brown glass we need to add sulfur, and carbon from coal. Brown glass, commonly known as, “reduced” glass, has a high level of carbon. This means it absorbs nearly all radiation consisting of wavelengths shorter than 450 nm, offering excellent protection from ultraviolet radiation and prevents skunking of the beer. The alternative to brown glass would be blue glass, which was also common in the 18th Century but to get blue glass, we have to add cobalt oxide. The beauty of cobalt is that as a colorant it is so powerful that only a few parts per million is needed to produce an intense blue color. The problem, of course, is that cobalt is also radioactive.
So, when you have the privilege of drinking authentic colonial beer from one of my not authentic bottles, take the beer but leave the bottle. There is a lot of science and a fair amount of work that goes into putting the beer in these bottles and that science goes well beyond the beer inside.