The Machinery at the Bark Mill @museum.de

If you’re wondering what a bark mill is – it’s simply a mill used to cut and grind bark ... and, by extension, the building in which that machinery is located. The machine on display here dates from 1888 and originally stood in the former Metzger tannery in Wilhelmsdorf.

Next to the milling machinery, there’s what’s called a fulling barrel. This large example was added in 1870. It would have held thinner skins that had first been rubbed with fish oil and beef tallow. The wooden drum rotated, driven by hydropower, and in no time, the five rows of wooden pegs inside the drum would have kneaded and rolled the skins in the fat mixture into supple leather.

The back of the room is dominated by a huge leather roller. It was set up in 1914 and significantly lightened the tanner's heavy workload. Previously, the tanner would have had to use a hammer to compact the damp leather by hand. The roller, by contrast, applies enormous pressure to the leather – around a tonne – compressing it into hard leather. The design is actually quite sophisticated. Have you noticed the wooden rod, mounted horizontally across the length of the machine? It was used to change the direction of the roller continuously – from left to right and vice versa.

Working with the wet, tough leather soon took the edge off the tanners' metal tools. The de-hairing blade, the fleshing knife or the tanner’s hook frequently needed sharpening. That’s why the whetstone rotated through a small tub of water – keeping it wet and always ready for use.