Vegetable oils are extracted from oilseeds and oil fruits in oil mills. Different processes using different technologies result in major differences in the qualitative and quantitative performance of oil mills.

The International Oil Millers' Association discussed such technical and other economic issues at a congress in Wiesbaden in June 1938. The large number of foreign guests was the reason for a reception in the town hall on June 23. Lord Mayor Mix thanked the organizers for choosing the spa town as the venue for the meeting. The congress participants expressed their delight at the beauty of the city and the region.

Afterwards, a total of 15 representatives from Europe, the USA and Asia signed the city's Golden Book.