How does insulation work in drinkware?
To understand, you first need to remember some high school science. Heat is transferred in three ways: Convection, conduction and radiation. Copper insulated drinkware works with all three.
In convection, heat transfer occurs when a liquid or gas — air, for example — moves. In other words, it works by moving heat from a hot liquid to the cooler air by the motion of the air. For example, when you blow on your hot coffee you are transferring the air particles, cooling the hot substance. In drinkware you want to prevent the heat from being transferred away from your liquid to keep it hot- or into your liquid to keep it cool. We accomplish this with the vacuum. There is a vacuum between the inside layer and outside layer. By eliminating gas from this space we eliminate the convection of the heat. There is little to no gas to transfer the heat through. Some of our drinkware comes with vacuum sealed lids- this would help eliminate convection cooling of your drink also. As the vacuums in drinkware are not perfect, and some lids are not vacuum sealed, eventually some convection occurs.
In conduction, the transfer of heat is through a conducting material, such as metal. Heat causes the molecules to start to move and transfer from the heated molecule to another molecule. This transfer continues until all the molecules around the hot molecule are hot. An example of this is putting a metal spoon in your hot coffee, it conducts the heat up the spoon and soon even the handle is hot even though it is not touching the hot drink. We eliminate heat being transferred out of your hot coffee (or tea, etc) with the double layer of stainless or acrylic. The interior layer does not touch the outside layer. This helps keep the outer layer cool for you to hold and prevents it from forming condensation when you have something cold in your drinkware. Simply put, the outer layer does not touch the inner layer so it does not come in contact with the temperature of the liquid. Double layered drinkware is very effective and usually suitable for casual coffee drinkers.
Radiant heat moves in a straight line away from your hot drink, heating up anything solid that it encounters. This form of heat doesn’t heat the air, it heats just solids. The metals that are in the direct path of the heat absorb it immediately. Once the metal has been heated up, they radiate that heat to other metals. Copper is an excellent conductor. It absorbs the heat the radiant energy is transferring to it immediately and radiates it back. Since the copper is attached to the inner layer of our drinkware this radiation of heat occurs right back into your drinkware. This helps keep your drink hot longer.