A barrel is a genius construction: a watertight container from wood without a single nail.
Principle
Staves (boards) are tapered at edges. When cinched by hoops — they press against each other and seal. The greater the liquid pressure inside — the tighter. A barrel with wine is more watertight than an empty barrel.
Making
Split oak along the grain (don't saw — sawing cuts fibers, barrel leaks). Shape staves. Assemble on temporary hoops. Char inside (for wine/whiskey — flavor; for pickles — disinfection). Drive permanent hoops — iron or wooden. Insert bottom. Test: fill with water, wait.
Uses
Sauerkraut: 50-100 l oak barrel. Salt pork: barrel with brine. Butter: small 5-10 l barrel. Apple cider: fermentation barrel. Water: cistern barrel 200+ l.
Lifespan
Oak barrel: 50-100 years. Plastic container: 10-15 years + toxins + garbage forever.