The teeth are made of copper, and the slider contains a neodymium magnet.

As you zip up, eddy currents form and dissipate as heat, giving you a nice warm sleeping bag / onesie / crotch / etc.

Some maths: Assuming a tooth volume of 5mm^3 which implies a tooth heat capacity of about 0.017 J/K, and assuming a pitch of 1 tooth/mm, to raise the temperature by 1 degree would require a force of 17N. I measured the minimum force to close the zip on my bag to be around 2N, but I'd say I usually approach it with a lot more than that.

So this means that to heat the zipper by 15 degrees as it closes would take about the same effort as lifting 25kg (60lbs). This is probably outside of most onesie owners' comfort zones. But do not despair! The heating could be spread out over a few passes, i.e. opening and closing the zip a few times. Almost practical!
-- mitxela, Jan 03 2014

Derivative Heated_20Onesie_20Zipper
[mitxela, Jan 03 2014]

Actually since most metallic zippers are brass or aluminium, this could be made as a slider retrofit. It would just take a little longer, a few more openings and closings.
-- mitxela, Jan 03 2014


(I suddenly feel the need to affirm that that isn't a self-bun. Thanks, autobunner ?)
-- mitxela, Jan 03 2014


Thermite paste ?
-- 8th of 7, Jan 03 2014


Blast, here I was trying to add magnets when all along there was a cheap, practical, safe, reusable solution involving thermite.
-- mitxela, Jan 03 2014


Magnets have this bad habit of finding little bits of debris and rock that they like and grabbing them and not letting go. Then they destroy everything.
-- WcW, Jan 03 2014


How is thermite reusable?
-- goldbb, Jan 09 2014


make the zip out of some resistance metal e.g. NiChrome, pass a small current through it...?
-- bs0u0155, Jan 09 2014



random, halfbakery