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Is there a way to safely cool a heated test tube quickly without cracking it due to sudden thermal stress in the glass? One thing that I tried was blowing on it, cooling it in slightly lukewarm water followed by cold water but this method kind of involves a "hope for the best factor". Is there a better technique?

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  • $\begingroup$ I searched a lot on how to prevent shattering of glass but everywhere it is advised to use other material than glass..!! See this : studyhelpfox.com/3107678/… $\endgroup$ – ashu Oct 4 '13 at 19:17
  • $\begingroup$ Are you trying to cool the tube itself or can the contents be equivalently cooled as well? I'd just dump a little bit of ice into your solution. Probably the simplest way to cool the tube down. $\endgroup$ – LordStryker Jan 24 '14 at 14:29
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Rather than working on your technique, check whether other test tubes are available.

Apparently, a glass-like material with a very low thermal expansion coefficent would be a good choice.

The glassblowing shop at the University of Delaware provides a nice overview of the possible materials and their properties, and there are definitely additional online resources, e.g. by manufacturers like Schott, Corning, etc.

Here's a summary (coefficients are given in $cm/cm/°C$):

soda lime glass $89 \times 10^{-7}$

Pyrex, Duran $32.5 \times 10^{-7}$

Vycor $7.5 \times 10^{-7}$

fused quarz $5.5 \times 10^{-7}$

Please note that quarz is both pretty expensive and demands special care! Alkaline solutions and quarz are a bad conbination!

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Regular test tube is not really a good choice for rapid cooling for two reasons:

  • it is often cheap glass,
  • it has a relatively thin wall, and large space for the sample inside.

This later is important, because if you want to cool down something really quick, it should be relatively small, and have good contact with the wall. I assume you want to cool something really quick or else the question has not much point.

  • Have you tried better quality tubes, e.g quarz, Pyrex?
  • Have you tried transfer the sample to a cooled place, instead of cooling the whole thing down? E.g. rapid freeze quench techniques are often based on squirting the sample into a large volume of cooler liquid or on a cooled surface.
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