While not important to your knowledge of rain water collection and storage, the following information about how wine barrels are made is quite interesting. The art of barrel making, known as cooperage, is an ancient skill. Despite improvement from modern research, analysis, machinery and wood selection techniques, the actual barrel making process has changed very little over the years and is extremely time intensive. To achieve the highest standards of quality, most of the work must still be done by hand by a highly skilled cooper.
Every season, when trees are felled, experts from the cooperage are on hand to select the best oak wood for use in the manufacture of barrels and vats. This selection is the initial phase that essentially determines the quality of the finished product. The oak is examined both before and after being cut, and wood is selected based on many criteria, including tree shape and growing conditions.
The logs must be hand split to preserve wood grain without breaking wood veins, which is essential for creating impermeable barrels. The oak log is first split in two, then into quarters to obtain wood for the oak staves. After splitting and planing, the stave wood is stored outside in tiers. Exposed to air and water, the wood is naturally aged by the weather for several years. During the aging process, the development of sugars and acids are monitored.
After aging, the staves are formed by machines into the proper shape and form for barrel assembly. After they are cut to the proper length, they are tapered at each end and beveled. Then they are planed on the outside, slightly hollowed on the inside and jointed by high precision machining.
After being inspected and selected, the staves are given to a cooper for assembly. At this essential stage of the manufacturing process, man steps in. The craftsman with irreplaceable experience and, above all, appreciation for work well done now adds his personal touch. The sharp-eyed cooper selects his staves, setting aside those that do not suit him. Then he assembles the staves inside a metal hoop that serves as the assembly jig.
Solidly held in place by three metal hoops that have been forced into place, the "rose" is then subjected to a trial by water and fire in the workshop, where it takes its final shape. Repeating movements that are part of the most ancient tradition of his art, the cooper seals joints by passing a wet cloth inside and outside the staves, then heating the barrel over a wood fire for approximately 30 minutes. Rendered flexible by heat and humidity, the wood fiber can now be bent by the cooper, who uses a winch to gradually arch the staves and tighten them to obtain the shape of the barrel body. The body is held trussed in place like this until the metal hoops are definitely placed.