Above the entrance of a building at the Graven in Deventer is this sign of 2 dark blue hands and a blue cloth. (Once) a launderette maybe? I had no idea..
Back home I googled and learned that the sign pictures the hands and the profession of 'Blauwverver Barthold van Ophuijsen'. This 'bluepainter' named Barthold van Ophuijsen lived here around 1600. His profession was painting people's clothes blue, a deep dark blue until they almost turned black. His customers were mainly people who were in mourning. Being a widower or widow meant wearing dark clothes for a long period, and having your clothes painted dark blue or black obviously costed a lot less than buying new clothes.