Market research#

Current products in the market utilizing sodium acetate trihydrate crystals#

Top: Hot Snapz brand hand warmers; Bottom: HeatWave brand handwarmers, by Bent Grass Concepts. Shown here is how one would make the handwarmer bag reusable. This list is not exhaustive.

How does crystal formation happen?#

Schematic of how current products work#

Above: Example of salt acetate-based hand warmer encased in vinyl bag. The flex disc has to be manually ‘clicked’ to trigger formation of crystals. The handwarmer can be reused by boiling the bag in water to melt all the crystlas. (Reference:, but annotations by me)

Above: Video of heating pad in action. (Reference: Wikipedia)

Design rules for triggering crystal formation#

Helpful tutorials and links#