Sometimes manufacturers make bottles with copper linings in an attempt to keep the contents even hotter or colder. It could work, and as Wesley Johnson, a cryogenics research engineer at NASA’s Glenn Research Center in Cleveland, explained, “For spacecraft, we often use a similar technique for insulation.” The theory behind using copper in insulation (despite its being an excellent conductor normally) is based on the fact that heat transfers through three forms: solid conduction, gaseous convection, and radiation, Johnson told us. A double-walled bottle already stops solid conduction, and a vacuum-insulated bottle stops gaseous convection. “This leaves only radiation heat transfer between the walls,” Johnson said. And copper can work to stop that last method of heat loss. But it works only under a set of specific circumstances. “The main benefit of copper is that when it is polished, it is much more reflective of radiation heat transfer,” Johnson explained. So, “the copper liner needs to be: polished, installed in a vacuum, and done so in a manner that limits the amount of oxidation of the metal prior to pulling the vacuum.”
