I'm doing a project where I freeze water drops and solutions with water and ethyl alcohol. It's a phenomena where drops create a conical shape at the end of their freezing. But with ethyl drops, with concentrations between 10% and 20%, they act weird. Most of them have a conical shape, but that shape, compared to shape of water, isn't symmetrical or they have weirdly shaped fragments on their tip. (not the usual fragments appearing after the drop freezes completely) Any information about heat transfer of ethyl alcohol or about ethyl in general would help. Thank you.

This is what I'm expecting it to look. 17% 01

Sometimes this happens 17% 02

Note: The temperature of the metal where I put my droplet on is about -40 degrees celcius. This rarely happens on -15 degrees. The drops on the pictures are the same: 1) they contain 10 microliters 2) the temperature is -40 degrees, and it's constant 3) both of the drops have 17% of ethyl alcohol

I assume all forces that affect on the drops are the same, so there must be something in the structure of ethanol that I don't know about.

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    $\begingroup$ When your solution freezes, it is water that actually freezes, and the rest of liquid gets enriched with ethanol. To freeze it completely, you would have to go way below -40. $\endgroup$ Nov 11 '17 at 15:51
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    $\begingroup$ I have considered that solution (no pun intended). The freezing point of 17% ethanol is between -4 and -9 degrees celcius. link @IvanNeretin $\endgroup$ Nov 11 '17 at 20:02
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    $\begingroup$ That's irrelevant. Solutions are not like pure compounds. They start freezing at one temperature (that's what your link gives) and do not freeze completely until another temperature, sometimes quite a while lower. $\endgroup$ Nov 11 '17 at 21:33