The purity of rectified spirit has a practical limit of 97.2 % ABV ( 95.6 % by mass ) when produced using conventional distillation processes .
A mixture of ethanol and water becomes a minimum - boiling azeotrope at this concentration .
The purity of rectified spirit has a practical limit of 97.2 % ABV ( 95.6 % by mass ) when produced using conventional distillation processes , because a mixture of ethanol and water becomes a minimum - boiling azeotrope at this concentration .