Cloudy white film on glassware

Hey guys,

First time / long time…

I’ve got cloudy white film on a lot of our glassware here, specifically round bottom flasks used for distillation and on the rotovap. We typically wash our flasks with acetone followed by an ethanol rinse before they go to the drying rack. I have tried a few things to get rid of this staining: a DI water rinse, hexane in case it was vacuum grease, a hot alconox bath and now I am out of ideas.

Has anybody dealt with this? It’s driving me crazy!

Thanks in advance!


Usually cloudy-white lab glass deposits are due to Calcium buildup, but it could be otherwise. Try using RO water for your final rinse and see if white vinegar (or Citranox) will remove your cloudiness.

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My typical approach to cleaning was an overnight soak in acetone, followed by an overnight soak in alconox (I kept extra glassware so there were always clean ones in circulation). That kept this problem at bay on all my glassware, expect for rotary evaporators where hard water evaporating could lead to mineral buildup. In that case an acid type cleaner can be helpful. CLR is a good example of a commercial cleaner based on this principle. An ODA inspector said I had the cleanest looking glassware of any facility she had inspected.


I often have luck with dawn dish soap and water, followed by isopropyl, and finally acetone.


Using goof off on warm glassware works pretty well, its mostly made up of xylene and acetone i think… Very aggressive solvent.

Water and vinegar then 99% Iso in a Sonic Bath, clean every time

It’s a lot of D limomene as well- surprised nobody has mentioned limonene as it’s kind of great for cleaning up glass but beware as it will eat through plastic real fast

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Simple green works great for me. I use hot water and simple green to carefully clean all my connections and then I use acetone and if there’s any chunks or weird stuff ill use hot water and simple green and salt. Then repeat

Thanks everyone. I brought some vinegar in today to try out. I have tried dish soap and RO to no avail. I’ve got some simple green here I could try. If the vinegar works I’ll look into some Citranox. I’ll let you know how it goes. I have some of the cloudiest flasks filled with vinegar in the sonicator right now.

Works wonders


I’m gonna try this next. I just ran some flasks in the sonic bath with 5% acetic acid vinegar for 3+ hours at 100F to no avail.

Of course the surest way to get your glassware perfectly clean is the old base bath. Isopropyl alcohol with added sodium hydroxide.


Caustic soda certainly crossed my mind. We shall see. I’m tired of cloudy glass. I’ll stop at nothing to get it clean.