Abstract: A heat producing apparatus includes a plastic container having flexible walls which are interconnected along a linear zone or zones; a supercooled salt solution is in the container, to be triggered and crystallized, to produce heat; and a trigger floats in the solution relative to the linear zone, and includes a bendable trigger strip, and a multiple member frame confining the strip, the frame and trigger movable together, relative to the linear zone or zones.

Abstract: A thin walled, light-weight, relatively flexible, molded plastic package has first and second re-entrant recesses respectively at opposite sides of the package, the package stiffened against crushing. The package includes:(a) the first re-entrant recess at one side of the package containing sufficient of a predetermined quantity of an expanded synthetic resin as to substantially fill said recess, and(b) the expanded resin cured to form a hardened re-inforcing core in said first re-entrant recess and integrally with the package to stiffen same against crushing, whereby an article or articles placed in the second re-entrant recess at the opposite side of the package are protected against crushing.

Abstract: A flexible mask includes a container for triggering of salt crystallization. The mask is manipulated to prevent stiffening, so as to be closely fitted to a human face to transmit heat thereto for therapeutic purposes.

Abstract: A protected trigger usable in initiating crystallization of a supercooled salt solution comprises a thin metallic strip containing multiple openings. The strip is protected as by a peripheral frame and/or by a metallic coating.

Abstract: A trigger usable in initiating crystallization of a supercooled salt solution comprises a thin metallic strip containing multiple pin-hole size openings, and which is bendable with snap displacement. The strip may typically be non-ferrous.

Abstract: A trigger to initiate crystallization of a supercoated salt solution comprises,(a) a thin strip having a perimeter,(b) said strip having a multiplicity of slits formed therein, each slit characterized as having opposed elongated edges which face one another in near touching relation,(c) the strip further characterized as having two configurations between which it is bendable with snap-displacement causing the slit edges to initiate progressive exothermic crystallization of said salt in the solution.