Expert: George Maxwell - 3/27/2008

Question
QUESTION: My husband and I can't agree.  Can a glass that once held alcohol still have "alcohol residue" on it?  He claims all the alchohol would evaporate over time.  Could a child safely drink out of a bar glass that once held alcohol?

ANSWER: Hi, and thanks for your question.

It is possible for some remnants of alcohol to remain in a glass for a while after drinking, but washing out will normally remove most traces (because ethanol dissolves in water). In any case, after about a week, the alcohol will oxidize in to vinegar, and no actual ethanol will remain.

in any case, remaining levels of alcohol would be almost undetectable. Much more concerning would be any bacterial / viral contamination of a bar glass, so a thorough washing in warm detergent would be necessary anyway, which would certainly remove any remaining alcohol.

Hope this helps,
thanks
George

---------- FOLLOW-UP ----------

QUESTION: So simply washing will rid the glass of all traces of alcohol anyway?

Answer
Even a quick rinse with cold water would remove most traces of alcohol (certainly below the level where they could be detected / would do harm). A warm rinse would remove them entirely. In any case, no significant amounts of alcohol will be present in the glass even before rinsing because, as I said, it will oxidise to vinegar very quickly.