Hair Elasticity

Cutting hair
Q: How does hair elasticity affect a hair cut that I will do, and also, what do I need to take into consideration when I am cutting someones hair and they have eyebrow piercings?
A: The elasticity of the hair affects the way you handle the hair when cutting it, since when the hair is wet it is easily stretched and will revert to its normal state when it dries again.
This means that with someone whose hair is very elastic, you could accidentally cut the hair significantly shorter than you intend. This is why it is very important to hold the hair using as little tension as possible in most cases.
A strand of hair can stretch as much as 2-1/2 times its length before breaking when it has good elasticity. It will return to its normal shape when let go. If it is wet, it can stretch more easily and can be more fragile and prone to breaking.
Combing out wet hair often stretches the hair somewhat, which is why most people notice that their hair seems much longer when it is wet. In a normal individual the hair will return to its normal length when it dries once more.
This shrinkage becomes doubly problematic when you're dealing with curly hair types. Curly hair can shrink 4 inches and more when going from wet to dry. This can result in a significant difference in the wet and dry lengths when you cut curly hair types.
As for cutting the hair of someone with eyebrow piercings: the piercings really don't have any bearing on a haircut unless they are somehow potentially in the way of the scissors when you are cutting the hair. If they are in the way, ask the client to remove them while the hair is being cut, and if they aren't in the way, treat them the same as you would any other piece of jewelry. You don't base a haircut on the type of earrings a woman is wearing, or her necklaces. Accessories should be considered secondary to the hairstyling.
That being said, if the piercings are sufficiently new that they aren't fully healed, you may want to advise the client that he or she should cover the piercing with a bandage during the cut to prevent hair particles from getting into the piercing and possibly causing infections or irritation.
See also:
How much hair will stretch
How do you get your hair's elasticity back?
If you get a perm. How much does your hair shrink up?
Should you not brush hair when wet?