Residual bourbon in glass question

[Jono]

On the rare occasion where I find some bourbon..(anykind of whiskey actually)...left in a glass overnight...it invariably has turned cloudy and tastes very off....so, is the obvious reason that most of the alcohol has evaporated and the remaining liquid is subject to oxidation?

[Stu]

I think that some of the alcohol may have evaporated, but I think that the off taste comes from the alcohol absorbing water from the air. I say this because I sometimes drink arak. If you mix any water with arak, it will turn milky. At times when I have a few drops left in the glass, I notice that it's milky the next morning. I notice a flat taste to left over whiskey, arak, cognac, or any other spirit left out over night. It also tastes diluted. I like my liquor straight. A way to overcome this is to use a Glencairn glass with a lid. Or I guess you could put a poker chip or something over any other glass. This keeps out the air and reduces the absorption of water.

[Jono]

Or....don't waste any in the first place! I think you are right..the combo of evaporation, possible precipitation if humidity is high, oxidation etc.

[ILLfarmboy]

I would attribute it mostly to oxidization. I had a bottle of Antique that I had used to fill a half pint "travel stash". The half pint filled up before what was left in the fifth was completely empty, about a teaspoon's worth. I put the "empty" bottle of Antique upstairs with several other dead soldiers. A year or so later when I went to wash out the bottles I noticed the thin ring of bourbon around the circumference of that concave bottom was cloudy, just like the last few drops of whiskey left in a glass overnight. It had sat in the upstairs closet through summer and fall where it was little effected by the air conditioner through the warmer months. I suspect the heat may have sped up oxidization.

[Jono]

I wonder if McKenna is chill filtered? Unfiltered whiskey can account for the cloudiness...but the bourbon was at room temp....though as an exeperimet I had placed the bottle in the freezer as a taste test. I don't recall it coming out cloudy.

This poster on another site noticed the same thing:

http://www.bourbonenthusiast.com/forum/DBvd.php?id=335&task=displaybottling