Shade Test

Hair with different shades
Q: Should a hair stylist always do a shade test before coloring your hair? How is a good hair shade test done?
A: Shade tests are not something that most stylists do on a daily basis. The reason for this is because it is basically has an inexact outcome.
A shade test is basically a procedure where the stylist takes strands of the client’s hair (usually hair that has been cut off), and first tests a specific color or shade on the hair. The main reasons for this is usually to try and see the exact color that a certain tint/color will have on a specific person’s hair, or to see how a person’s hair will react to the tint/color in question.
The reason that we say that this is an inexact procedure is because you’re limiting the test to a very small amount of hair. The hair “monster” that you’re exposing to the color is not necessarily identical to the rest of the hair on the person’s head for a number of reasons:
1. Tips of hair (most likely the kind that will be subjected to the strand test after it has been cut off) tend to be drier and lighter than hair at the roots. This is basically because tips are older and have been exposed to a lot of chemicals, heat and natural elements. Thus, the shade test’s result on the tips of the hair will look different from the result that you’ll get on the roots.
2. Hair on top of the head is usually lighter than hair at the bottom, due to natural bleaching of sunlight and heat. People also tend to go gray first at their temples and crowns, while the hair at the back of their heads is still natural colored. This means that the color result that you get on one hair strand can potentially differ wildly from another strand from different vicinity on the head.
Thus, theoretically the best strand test would be if you could do the test on a sufficient amount of full-length strands, but this is often impossible, as you can’t really pluck wads of hair strands out of the client’s head in the name of “A perfect strand test”.
Strand tests can be very valuable if you want to see if hair is healthy enough to be exposed to high-risk chemicals such as bleach and chemical straighteners. Yet, this is also a very inexact science as no one strand is identical in health, color or pigment. For these reasons, strand tests are not used very often, and definitely not before every color-service.
See also:
How to color hair
Hair porosity test
Hair patch test