Around 100 years ago, there was a whole community here at Karlsfors. There was a bank, a post office, a school and a store. The industrial community started with alum production as early as in the 18th century. The alum was for example used as an ingredient for red paint. In the middle of the 19th century the industry shifted to mainly produce lime for cement and soil improvement. Today you can only see the remains of the industry.
You are now inside the saffians building, the largest of the alum production buildings. The inside of these masonry walls once contained 40 large wooden vats. The refined alum shale came here several weeks after it had been refracted from the mines. Follow the long way of the shale from the mountain:
1. Alum shale is hacked out in open-cast mines.
2. The shale is taken to an open place and burned in piles.
3. In the soda shed the burnt shale is put into Iarge vats of water. "Alum liquor" is released.
4. The liquor is conveyed over the hill to the boiler room in a channel of hollowed-out logs. It is then seethed in big lead boilers for two days.
5. As the alum cools in the boiler room, a yellow precipitate, iron sulphate, is formed. This is dried in lumps and crushed in the mill to be sold as red paint.
6. The luke warm alum liquor is transferred to wooden vats here. Concentrated alum solution is formed.
7. The solution is dissolved in warm water in the refining shed and kept for a fortnight in big barrels. Pure alum crystallises out.