What sets Spirit Steels apart from other products on the market is the ability of the internal material to go through a phase change i.e. frozen solid to melted liquid and vice versa. This material allows them to absorb 6-10 times as much heat as the solid metal or soapstone equivalents, keeping drinks cool.
The phenomenon that happens inside is called “heat of fusion”. Heat of fusion is the amount of heat required to convert a solid to a liquid WITHOUT changing its temperature. This is important because solid metal or soapstone never changes phase, well at least not at temperatures you would want to be around!
Spirit steels are made from a thin walled stainless steel that is filled with a food safe liquid. The magic happens when you put these into your freezer, the liquid inside changes phase to a solid and in doing so, releases a TON of energy in the form of heat. When used they will absorb the same amount of heat when transitioning back to a liquid.
The chart below shows a performance comparison of Spirit Steels to other cooling devices on the market. These units were pulled directly from the freezer and placed in an empty glass. As you can see the soapstone heats up VERY quickly, meaning it can’t absorb a lot of heat from your drinks. Spirit Steels reaches 33° F and then “flat lines”. This flat line is when the material inside is changing phase.