Re: Cleaning cast iron
As far as I'm aware, the thing to ensure is that it always remains treated with oil/grease. So scrubbing clean with just water after a normal meal is fine, because it doesn't take the oil out of the surface. Sometimes like you say I find it necessary to use regular dish washing liquid, after which I always drizzle oil back over the entire pan and rub some in with a cloth.
I'm sure there are more die hard cast iron people around with better treatment of their pans, but this is how I do it!
, for all things painted and dyed.