Chemistry project on hand warmers: Salt hydrates

Currently I am working on a chemistry project about hand warmers. My goal is to find a salt hydrate which gets warmer than sodium acetate trihydrate and can supercool. I already bought magnesium nitrate hexahydrate and aluminium ammonium sulfate dodecahydrate. I have tried to supercool them but they always crystallised so far.


Do you know if it is possible to supercool them? Can I mix two of the mentioned salt hydrates? For example, sodium acetate trihydrate and magnesium nitrate hexahydrate?


