This excellent infographic shows how the flask evolved from a rudimentary animal bladder in the Stone Age to sleek stainless steel vessel it is today. Over time, the flask or canteen has evolved from being a personal carrier of liquids to being almost exclusively for the transport and consumption of hard alcohol.
Through history, there have been some important developments in the transportation of liquids. Before the modern era, alcohol was useful for its preservation and sterilization properties when clean drinking water was hard to find. Drinking alcoholic beverages, such as beer and wine fermented from local crops, was first foremost a practical health measure. One needed to carry trustworthy liquids with them and as a result, nearly every culture developed their own form of a flask.
Some say it all started with the hunter-gatherers of the Kalahari, in Southern Africa, 60,000 years ago: they used ostrich eggshells as canteens. Earthenware containers evolved around 2000 BC and were eventually replaced with more modern materials such as glass and metal. From approximately 500AD to the Middle Ages, Pilgrim flasks were created by the thousands for Christian pilgrims to take home water or oil from a sacred place.
The modern flask – a sleek beverage bottle – may have started with the advent of the pocket watch. The notion of carrying something in an easy and practical way developed in the 18th century in England, but followed different ways: the landed gentry adopted the pocket watch and the workers started carrying the hip flask.
It's not exactly known when, but it was approximately at this juncture when the flask was beginning to take the modern shape with a rounded rectangular body that was curved to match the contours of the body. This shape makes it less visible in the pocket than a square-edged shape.
Prohibition and the Flask in America
Prohibition radically changed drinking in America, and as you can imagine, if you wanted a drink it was best to conceal it.
Around this time, the watch and the hip flask traded places: the wristwatch became commonplace (it surpassed the pocket watch in the 1930s) and the hip flask found its way in the urban gentleman's collection of accessories around 1920 when it gained its name.
The word "hipster" was used to identify people that carried hip flasks during Prohibition. Also, if you carried a flask, you were dubbed a vial villain, a gentleman from Kentucky or my favorite, suffering from hip disease.
They were also carried by ladies tucked in garters or by men in boots – thus the word "bootlegging".
Some states, such as Indiana, banned the sale of hip flasks and cocktail shakers. This was probably due to the fact that more flasks were sold in the first six months of Prohibition than during the entire previous decade…
In the mid-20th century, the most prominent users of flasks were soldiers, who carried canteens out of necessity. During World War II, they were called pocket pistols, along with other slang terms; on the other hand, RAF pilots referred to their service revolvers as hip flasks.
Today
Today, in a world in which every imaginable specialized beverage container is available, the flask is used primarily to carry one's private supply of hard alcohol. It's commonly given as a groomsman's gift.
Hip Flask or Coat Flask?
It is so called because it may be placed in a hip pocket of trousers or inside a coat or blazer. The latter is the best because it will not warm the alcohol, while the hip pocket will.