In order to understand Technical alcohol we should understand How alcoholic compound behave in distillation column. Technical Alcohol are mostly classified in to three group based on thermodynamic properties, some of these impurities i.e. Easters, and many aldehydes are most volatile than alcohol and found at the top of the column are called commonly called heads compound.
Most of organic acid like phenol compound which is less volatile than alcohol which are found at the bottom of distillation column, are called as tails compound.
Third Group of product id Fusel Oil-this product is more volatile than alcohol at low alcohol concentration, and less volatile in high alcohol concentration. This type of beaver are collectively call fusel oil, and all above three category called technical alcohol. (Impure Spirit). This Technical Alcohol can be saleable as a Special Denaturant Spirit(SDS).