Labeling is required by law. The container must provide the full name of the substance with no abbreviations. In addition, hazardous chemicals must also contain basic warning information. The basic warning information is the following: The Chemical Lab group the waste originated from, Full name of the chemical waste (No abbreviations), Percentage of chemical waste constituents to total 100%, Hazardous designation (ignitable, toxic, reactive, or corrosive), and The full date when each bottle has been filled to 80% capacity.
When reusing a container make sure you either remove or completely deface old labels to avoid confusion. Inspect labels and replace those that are hard to read or have fallen off. Good labeling practices avoids accidents and reduces the disposal cost of chemicals by eliminating subsequent unknowns.