The mixing glass is a critical tool to the mixologist for those cocktails that need to be stirred instead of shaken.  Stirring cocktails allows the bartender to control the chill and dilution of the cocktail better than shaking and straining.

Originally, mixing glasses were just the pint glass of the Boston shaker, since they were readily available and it minimized the need for additional items on the bartop.  Today, mixing glasses come in many different materials and sizes, and a properly selected mixing glass can represent the mixologist’s personality, whether the bartender’s using it or not.  Mixing glasses are most commonly made of glass, and the thickness of the glass will vary according to design.  Because the intent of using the mixing glass is the get the cocktail as cold as possible, the glass should not be so thin as to transfer the heat from the hand stabilizing the glass (and become brittle), nor should it be so thick that the glass is hard to hold.