When I buy some ice cream from a parlor or get some from the supermarket I find that the containers (also the standard bowls I can find in my kitchen) are not perfect for eating ice cream from. The problem is that the ice cream already starts to melt on the edges and on the bottom when eating it from top to bottom. I'd like to eat my ice cream from top to the bottom of the container without having to worry about the edges getting liquid.
I know that the shape of the container (how much surface area it has) is important too, but from what I as a layperson understand the thermal conductivity of the material is much more of importance in this scenario. I already searched the internet and found some comprehensive lists of different materials and their thermal conductivity but those lists don't really make a difference between food safe or not and apparently thermal conductivity also changes with the temperature of the materials.
My last physics lesson was over a decade ago and I have to admit I'm simply lost. What I'm looking for is the material best suited to put ice cream in and the ice cream should melt considerably slower on the edges than the top that is exposed to air. The material should be safe to eat from, and it should be possible to actually make an affordable bowl from it (i.e not made of diamond). I assume an room temperature of 20 °C (or maybe 35 °C on a hot summer day).
The best I could come up with so far, although more from experience than based on science, is a wooden bowl.
Best Answer
Why not put the bowl in the fridge or freezer before so that it is cold?
There is an interplay here between heat conduction (how fast the bowl equalises temperatures between ice cream, bowl material and air) and heat capacity (how much thermal energy is in the bowl, ice cream and air). If you had a bowl with a great deal of heat capacity and a low initial temperature (say a thick porcelain or marble bowl you had put in the freezer beforehand) then it would help keep the ice cream cold, but the same bowl at room temperature would of course just act to heat the ice cream to room temperature more efficiently. One interesting approach is of course to freeze ice into bowls - low temperature and a big heat capacity (maybe even too large; in my opinion ice cream should not be served too cold).
A bowl with small heat capacity and low thermal conductivity would itself not contribute much to heating, but would keep the ice cream insulated from the air and body heat. One approach would be a thin metal bowl (small heat capacity) surrounded by something fluffy (low thermal conductivity), perhaps held in some further convenient shell (like another metal bowl, or a wooden bowl). Think of how a thermos flask works: there is an insulating layer of air (low conductivity) between two metal shells (themselves kept in place using rubber or plastic fittings).
Diamond is a pretty bad ice cream bowl because of its high thermal conductivity and relatively large heat capacity; always chill diamond bowls before serving!