Does anybody have any idea of whether or not a non-metallic trigger could be used in sodium acetate heat packs. The crystalisation preocess in the packs is triggered by bending the metal disks inside them which causes heterogeneous nucleation. Are there any plastics which could work where scratching or bending them would expose the crystals that might then act as nucleation sites for the sodium acetate. I've heard of plastics you can get that contain filler materials, but does anybody reckon these may work or know where to get hold of them. I'm looking to replace the metal trigger in the pack with a plastic one for a product design application.