Post #708405 by Chip and Andy on Mon, Feb 17, 2014 8:16 AM

Lots of reasons for the float.

One of the primary reasons is to keep the drink at the desired proof top to bottom. As you sip the drink through your straw, the ice is melting and slowly watering the drink down. As the drink gets lower in the glass, the ice is melting faster and watering the drink down more and more. By adding a float of liquor on top you are adding a level/layer of alcohol that is combating that additional water. It makes the 'bottom' of the drink taste as good (hopefully) as when you took the first sip.

Floats can also be simply for looks, a nice layer of whatever on top can be visually interesting.

And as a general rule any drink that has a float is going to be served with a straw. Otherwise the first sip of the drink is the float and if you are floating overproof liquor then you're going to burn out the tasters and the rest of the drink will not be enjoyable.