Final answer:
The four classifications of hair coloring products in cosmetology are temporary, semi-permanent, permanent, and demi-permanent.
Step-by-step explanation:
The four classifications of hair coloring products in the field of cosmetology include temporary, semi-permanent, permanent, and demi-permanent.
Temporary hair colors are usually used for special events and occasions and wash out after a few washes.
Semi-permanent hair colors last for several weeks and gradually fade over time.
Permanent hair colors are long-lasting and require regular root touch-ups as the hair grows.
Demi-permanent hair colors are similar to semi-permanent but can last a bit longer.