brilliant. perhaps it could work like an electric blanket. have a rechargeable battery pack in the jacket or other clothing. just plug in for a while before going out and enjoy added warmth.

Brilliant -- can I heat up my clothes right now!

Until someone leaves a coin, key, or lighter in their jacket and blows up the microwave and your ridiculously expensive clothes.

A phase change material could be encapsulated and slowly change phase back to solid giving off heat.

This is already in use in passive solar aplications.

SRB

Apart from car keys etc as mentioned above, no metal zipper either. Otherwise the idea sounds great just. The electric blanket idea may just be easier, though ...

EmeraldFalcon has a pretty good knack for finding potential problems, and if he/she were capable of presenting them in a useful and constructive manner, his/her opinions would be valued, would he or she would be considered a valued consultant.

Instead of a jerk.

I'm not even asking that he/she try to come up with a SOLUTION to a problem, God forbid. Let's just start with pointing out problems in a civil fashion; I know Mommy isn't around to scold you for not being nice, and that you're having a field day because of that, but.

The problem mentioned above doesn't apply to certain articles of clothing: the ones that don't have pockets. (hats, gloves, scarves, mittens, etc). That takes care of that.

A SOLUTION to the problem mentioned above might be this: a removable lining of the jacket, and that's what goes in the microwave. This also solves the problem of metal buttons and zippers and pocket items. Someone who is willing to spend the extra money on a heat retention jacket is pretty likely to be willing to deal with the removable lining (which has been around for a while anyway, right?). Maybe there are just a few strategically placed Velcro strips that hold it in place (although I don't know how Velcro would hold up in a microwave, to be honest).

Or maybe the jacket is made entirely with no metal, and we move the solution somewhere else: Metal detectors on microwaves.

The dryer episode from Seinfield with Kramer comes to mind. A number of people would love this if it can be convenient & cheap.

Excellent Idea!!!!!!!!

The material you are looking for already exists in microwave popcorn bags. It is a partial conductor, like a resistor. It does not cause microwaves with any problem.

I'm sure this could be coupled with a high heat capacity material similar to water to retain the heat for a long time. It might be more versatile to have 12 volt heating elements co-located by wrapping the resistive material around the 12 volt heater to prevent conflict with the microwave and provide versatility when away from the microwave.

Excellent Idea!!!