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We have an issue with our wash bottles. In our electronic lab, our students use isopropanol and acetone to wash manufactured parts. Unfortunately, we noticed a great deal of evaporation over time. After about one month, the wash bottles are empty.

Is there any better kind of container for such use? Or is there something that we are missing?

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    $\begingroup$ Evaporation, or use? If used infrequently, only fill with the amount needed. $\endgroup$
    – Jon Custer
    Commented Jul 27, 2022 at 14:18
  • $\begingroup$ I guess it is more evaporation than use $\endgroup$
    – nowox
    Commented Jul 27, 2022 at 14:22
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    $\begingroup$ Use less bottles or smaller; perhaps closing completely when not in use. $\endgroup$
    – Mithoron
    Commented Jul 27, 2022 at 14:57
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    $\begingroup$ BTW a month is supposed to be fast use? I doubt even a week would be. $\endgroup$
    – Mithoron
    Commented Jul 27, 2022 at 15:16
  • $\begingroup$ Are the acetone and isopropyl in separate bottles? $\endgroup$
    – llama
    Commented Jul 29, 2022 at 4:09

2 Answers 2

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First, do not put volatile inflammable substances inside a normal refrigerator as there is a very good chance you will get an explosion. As an example (my recollection, going back 30 years) some rats which had been euthanized with ether in the university where I worked were inside a plastic bag in a normal fridge. In the early hours of the morning there a spark from the internal thermostat exploded the fridge and set fire to the lab, burning it out. Sufficient ether had diffused from the bag to form an explosive mixture in the fridge. Following that, all lab fridges were fitted with external thermostats and marked as "safe".

Personally, I use drmoishe-pippik's 2nd suggestion when I'm cleaning paint brushes by putting the brush, in its container of solvent, inside a tin with a press-in lid (I don't use a plastic container as many solvents will permeate through plastic). I use the same approach with small containers of glue and in both cases, there is greatly reduced evaporation. This is the approach I would recommend for your acetone and IPA bottles.

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    $\begingroup$ + for noting that these liquids can evaporate trough plastic. Using food-grade containers sometimes helps. Glass or metal are, of course, better, but they have their own practical issues. $\endgroup$
    – fraxinus
    Commented Jul 28, 2022 at 10:47
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    $\begingroup$ Added +1 for safety comment! Acetone is less volatile than ether, but still of concern, even at freezer temperature, so I've modified my answer accordingly. $\endgroup$ Commented Jul 28, 2022 at 18:56
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Acetone is very volatile at room temperature, isopropanol a bit less. Not only is the solvent evaporating, but the ratio of acetone:isopropanol changes, making it less effective.

A few suggestions:

  • Use a wash bottle with a tight-fitting cap for the nozzle:

Wash Bottle with cap

  • Store the bottles inside a larger, completely-sealed container between uses.
  • Use a pump-type bottle (it might be hard to find one not attacked by the solvents).
  • Put a screw lid on the bottle if storing for a few days. *Possibly, store tightly capped bottles in a freezer between uses. As noted by Ken Mercer, evaporation in a refrigerator could cause fire or explosion, but the vapor pressure at freezer temperature, ~240 K, is 10 mm Hg (1,300 Pa), less likely to cause a flammable air/acetone mix. That said, this might still be a fire hazard!

N.B. Acetone is highly flammable, and, as the SDS states, "Can be ignited under almost all ambient temperature conditions." One hopes the technicians use it in a hood designed for fire suppression.

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    $\begingroup$ What this answer sort of but doesn't quite say is that wash bottles are not really intended for storage of solvents. $\endgroup$
    – jovisg
    Commented Jul 28, 2022 at 6:41
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    $\begingroup$ "Store the bottles inside a larger, completely-sealed container between uses." - isn't it safer to store them in a well-ventilated area? Otherwise, come the time to open the container, it may well be filled with a pressurised explosive mixture. $\endgroup$ Commented Jul 28, 2022 at 18:00

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