Hi Tim

This may sound a silly question, but has your post changed since I started to reply or am I just losing it?

The German Wikipedia page on Kaolin has a list of locations for mining, and here are a few pictures I have found of wagons:

http://www.bahnbilder.de/1024/kesselwagen-fuer-fluessigkaolin-md-papierfabrik-545432.jpg

http://www.bahnbilder.de/bilder/br-363-108032.jpg

and on the narrow gauge:

http://www.panoramio.com/photo/63334943?tag=railway

I couldn't find anything on historic wagons though I'm afraid.

This company claim to be second biggest Kaolin seller in Europe:

http://www.akw-kaolin.com

Brian