[Floreaa]

Yesterday, as i was doing some experiments in the chemistry lab, I dropped a piece of aluminium foil on the bunsen burner. The flame was turned on so I wanted to take the piece of aluminium and trough it to the garbage. As I was wet on my hands, a droplet of water fell on the aluminium foil that was situated on the burner. In stead of vapourising itself, the droplet turned spherical and stayed so for at least 15 seconds before vapourising. As it became spherical, the fact itself intrigued me because it seemed that the aluminium foil (that under the action of the flame probably turned into Al₂O₃) had some hydrophobic properties at that temperature.

The only thing that crosses my mind is that the margins of the water drop continously evaporated so that it turned into an almost perfect sphere. Anyway, I can't figure out why it took so long for the droplet to turn into vapours.

Does anyone have a clue af what really happened there?  thanks.

[nj_bartel]

http://en.wikipedia.org/wiki/Leidenfrost_effect

[Floreaa]

Thank you very much! It helped a lot.