I'm considering to buy a tetsubin, because the tea stays much longer warm (that's what I read everywhere). Often the inside is enameled, for rust-prevention. But how do you prevent the outside for rust? Wipe the in- and outside with a dry towel, when the tetsubin is still warm, that's what I've read. But that seems not enough to me, for a period of years.
With my cast-iron grillpan (Ronneby Bruk; non-enameled) it's easy: After every use I put some olive oil on a cloth, and I polish the pan, and heat it at my stove. So, I thought I can do the same with the outside of the tetsubin. But I've read I can't do that, because the inside enamel will crack.
Another question: Are there also tetsubin's which are enameled at in- and outside, just like Le Creuset pans? And if not, why is that?
Allready thanks for the answers.

Greets, Marco
P.S. Porcelain is maby also interesting to me.