The Great Beverage Debate

Bottles or Cans?

Have you ever gone to the fridge to take out a drink and chosen a can over a glass or plastic bottle because it’s colder? You wouldn’t be alone in thinking this. When you sit on a metal chair, it’s colder than if you sit on a plastic one right?

A friend of mine had this same logic when we went to a cafe once. She requested that her milkshake be brought in the metal tin it was made, instead of being poured into a glass. She told me that it’s colder that way. At this point the frustration was building in my physicist’s brain and I had to explain this common misconception as I’ll explain to you now.

First of all, if I have a metal and wooden object in a room, the metal object is going to feel colder. That’s a fact. However, the temperature in the room is constant so both objects should be the same temperature as the room. This is also true.

So if both objects are the same temperature, how can one feel colder? It’s because when we touch something, our fingers are actually measuring how much heat is being taken out of them. A metal is really good at allowing heat to flow so it easily takes heat from our fingers, making it seem cold. Wood doesn’t take heat from our fingers so well, so doesn’t seem as cold.

For this reason, my friend’s milkshake tin would actually feel colder because of the heat it takes from her fingers. The important thing to remember is that if it takes heat really easily, it also passes it on easily. Meaning that the heat from your fingers is going straight through to your milkshake. Not much heat would flow at all if a glass was used.

So the next time you want to choose a can from the fridge because it’s so cold, remember that if it feels colder, it will heat up quicker. For a prolonged cold beverage, choose glass or plastic instead.

2 Responses to “The Great Beverage Debate”

  1. Anthony Agosta says:

    Great post Lloyd.

    So are absolutely correct. The main reason for this is that Aluminium has a much larger thermal conductivity than soda-lime glass (which is the material used to construct glass bottles). Also Aluminium acts like a conductor, whereas the soda-lime glass acts like an insulator. Each material has its own advantages/disadvantages (with regards to heating and cooling) depending on what you actually want.

    For instance, if you come home from Dan Murphy’s on a hot day and put both aluminium canned and glass bottled drinks into the fridge (the aluminium cans will cool faster – so it’ll be your best bet for a quick cool drink). But as you mentioned, once you take it out of the fridge it will also absorb heat from the atmosphere while you are drinking it at a faster rate than a glass bottled drink (due to its higher thermal conductivity). To get around this, you can use a ‘can cooler sleeve’ (which acts to significantly slow down the heat transfer process), keeping your drink cooler for longer 🙂

  2. Callum Fitzpatrick says:

    Totally agree. Aluminium cans are probably the worst at holding heat. Aluminium is what computers use for heat sinks because they diffuse heat so easily, and the cans are really thin, just like a heat exchanger (which transfers heat as efficiently as possible)

    I imagine they’re great for cooling them down in the freezer though.