thanks. i ended up shopping around and found a adequately sized and
favorably priced heat pad. i called the manufacturer/importer and asked a
series of questions (how hot are the three settings and how long it is ok to
leave it on) and then asked if they thought it would be ok to use as a seed
warming mat and i was astonished they said yes. (i assumed they would be
afraid to expose themselves to a potential law suit if i burned my house
down using their pad in a non-usual way.) (my intent is to leave it on
almost/probably continuously for like a month or two.) (the heat pad is a
dual "dry/moist heat" pad and is designed to be used in close proximity to
moisture.)

(but to remain on metalworking topic, i posted the link for machinists with
cold feet.)

b.w.





It does, however, need to be very waterproof.

The OP could always try an old heating pad in a plastic bag.

--RC (who lives where seed warming is the least of his problems.)