Wanting to know more about the care and usage of Bannetons I took the trouble to do a rough translation from German of the usage page on the Brotformen site. I'm no German speaker so I cheated and used one of the translation add-ons available in Firefox.
Care and Cleaning of unlined Bannetons.
1. Flour your unit before use with rye flour.
2. After use, let the unit dry out and brush out so as to not let a thick layer of flour build up.
3. Depending on usage, every 4 - 12 weeks pre heat your oven to 120 - 140 C, switch off, and put the unit in for about 45 min to sterilise, then thoroughly brush out with a stiff bristled brush.
If you are lucky to have a UV steriliser unit then use it instead.
Personally I think in humid weather the sterilisation may need to be done more often.
Hope this is of help
regards
Bill
Replies
Detailed notes on how to care for bannetons and how to prepare them for the first use.
http://sourdough.com/blog/how-care-bannetons
Graham