How can evaporation from a wash bottle be prevented?

Question

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?

Answer 1

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.

Answer 2

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:

• 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.