On 17/03/2021 21:51, Chris Hogg wrote:

I'd have thought that this would dry out with regular microwaving
(although it does depend a bit on the porosity of the plate and the
amount of damaged glaze).

I'm nor sure that it does. The pores are small, in the order of a
micron or less, the vapour pressure of water in fine pores is
significantly reduced, and diffusion paths to the outside are narrow
and tortuous.

I've always attributed my plates and mugs that get "warm" to a slightly
conductive glaze (on the basis that the colouring is often given by
metal oxides some of which are slightly conducting).

They may be conducting when in solid crystalline form, but many
colouring oxides dissolve in the glaze and are present as isolated
ions. Although having said that, some pigments that are used these
days are insoluble, but whether they're conductive, even weakly so, I
don't know.



CAN I JUST SAY FINALLY THAT MICROWAVE HEATING IS NOTHING TO DO WITH WATER!!!


--
€œA leader is best When people barely know he exists. Of a good leader,
who talks little,When his work is done, his aim fulfilled,They will say,
€œWe did this ourselves.€�

ۥ Lao Tzu, Tao Te Ching