@solarmerps there are a surprising number of uses for wax with a known, controlled melting point
it's also how some fire sprinklers work! They consist of a valve that's pulled open by a spring, except the spring can't move because it's embedded in solid wax, so they stay closed. when the wax melts, the spring opens the valve and lets the water out
other types of fire sprinklers work by boiling a liquid to increase pressure inside a tiny glass tube until it shatters, releasing the spring
-F
@solarmerps there are thermal fuses that work the same way, only with electrical contacts instead of a hydraulic valve, too
-F