This is a big oak wine barrel as we use it in Alsace. Depending on the size barrels like this can contain from 6.000 to 8.000 liters. Some barrels are over 100 years old.
They are not used to work on the tannin's of the wines. In the old days we simply did not have stainless steel tanks. Today they are still used though, because they "breathe".
Inside a barrel you will find a heating element.By heating up the juices the winemaker can start and control the temperature and with that the proces of fermentation.
Did you ever wonder how they would clean a big barrel like on the picture above, from the inside?
By climbing in: ...... on the picture you can see the boot and leg of a man that got in and is brushing and washing the inside. Not for claustrophobics ...