[cat]

Hello,

When making an acrylic box today I used some dichloromethane to 'glue' the edges, and noticed minutes after that ice crystals - like snowflakes - formed on the brush I had used. Could anyone please explain what's going on there chemically? And what other substances does/can this happen with? I'd like to make more 'snowflakes' at room temperature! I'm a complete novice, so any info/suggestions would be much appreciated!

Thanks.

[Borek]

Was it really ice or did it just looked like ice?

[ARGOS++]

Dear cat;

Are you taking about real ice-crystals build from the moister of surrounding air on the top of the brush when the DCM volatilized, then it is only a physically process, because volatilization requires a lot of heat and that cools the top of the brush and the surrounding air in such a way, that ice-crystals start to grow at the “coldest” place.
(I did some similar experiments.)

I hope to have been of help to you.
Good Luck!
                    ARGOS⁺⁺

[azmanam]

I've seen this on the tip of my DCM wash bottle occasionally.  It's gotta be a solid forming as a result of the heat loss during evaporation of the solvent (bp 40 degC).  It can't be solid DCM, my lab mate and I both think it's water.

[macman104]

I see this all the time on my DCM wash bottles as well, I always assumed it was ice crystals from DCM evaporating as well.

[cat]

Here you can see what the crystals looked like on the brush. Thanks for all the replies. They are water crystals that melt to the touch.

Was wondering, why do they only for on the brush, and not in the container it was in, which was also exposed to the air? What is causing this reaction specifically on the brush? Is it the large surface area perhaps? Also, are there any substances that do this that are non-toxic? i.e. edible? Would be great to make miniature ice-cream snowflakes! Thanks again!

[ARGOS++]

Dear cat;

It’s exactly as I told you.
You can in a certain kind compare the situation with your car-windows in the winter time, expect that the cooling is done by the volatilization of the solvent, in your case the DCM.
But I don’t know a really non-toxic solvent with such a strong effect.

You 're welcome!   ─   Soon again.

Good Luck!
                    ARGOS⁺⁺