I'd suggest the fine glass fibre matting often used for a smoother
finish than the coarse chopped or rolled weaved matting

You can get a grade that's very thin, almost like tissue paper. I
have a roll of 50cm x several hundred feet of it that I snip the odd
bit off for heat insulation, works well. Enough material to electrically
insulate, but open to allow heat through

Any fibreglassing concern, such as a boatbuilder, will likely let you
have a square foot if they have a heart. Another layer of it over the
wire, wrapped with aluminium foil to help reflect the heat inwards,
then a layer of fluffy insulation, perhaps topped off with cardboard
to hold it all together

A long time ago I made a heated lid for a vacuum laminator which
was big enough to take two A0 sheets. I bought a mains-voltage
2000W heating element, which was nichrome wire embedded in
ceramic powder in a thin copper tube, which could be earthed.

Bendable to about a 2" diameter I think. It was very long, perhaps
25m, enough to be zigzagged on the lid's metal plate. Probably the
sort of thing that would be used to heat a tank

Just wondering if it's domestic cousin, a kettle element, could be
used, with suitable temperature monitoring. Perhaps a shallow tray
rather than a tube ?

Joe
--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.