| Hair
increases its length when humidity increases. So curly hair
frizzes and straight hair goes limp. From dry to humid, hair
length can change by 3 percent.
What do you need:
* Corrugated cardboard about a foot long
and 9 inches wide
* A piece of thin cardboard
* A pair of scissors
* A knife
* A pushpin or other large-diameter pin
* A straight or common pin
* A strand of hair that's one foot long
* A hot glue gun
* A dime
What to do:
1. On the top edge of the corrugated cardboard,
cut two slits about 1/4 inch apart and 1 inch from the left
side.
2. From a piece of thin cardboard, cut out a triangular pointer
about 6 inches long.
3. Cut two slits along the bottom of the pointer about 1 inch
from the left edge.
4. Attach the pointer to the base with a pushpin 1/2 inch
from the left edge in the center. Then take the hair strand
and slide it through the top two and bottom two slits.
5. Hot glue the hair in place in both sets of slits, then
hot glue a dime 11/2 inches from the left edge of the pointer
base.
6. Push a pin through the hole in the pointer so that the
hair is slightly stretched when the pointer is horizontal.
7. Calibrate your hair hygrometer at 100 percent humidity
by bringing it into the bathroom when you shower. Make a mark
when the pointer stops. Then use a hair dryer to dry the hair
and make a mark for 0 percent humidity.
8. Monitor the changing position of your pointer as the humidity
changes.
Hair is made from keratin, a protein that is wound into a
coil. The turns of the coil are held together by a type of
chemical bond called a hydrogen bond. Hydrogen bonds break
in the presence of water, allowing the coil to stretch and
the hair to lengthen. The bonds re-form when the hair dries,
which allows people to style their hair simply by wetting
it, shaping it, then drying it.
Hear Test
Wrap the strand of hair around your forefingers
so that your fingers are about an inch apart. Pull the hair
slowly, but firmly.
Can you feel the hair stretching out?
Healthy head hair will stretch when you pull
on it. That's because the cortex of healthy hair is strong
and elastic. The cortex inside of a damaged hair strand is
weak and brittle. It will break more easily when you pull
on it.
Creating curls
Hold up a single strand of hair. Pinch the
hair between the fingernail of your thumb and the fleshy part
of your forefinger.
Run your fingernail across the hair strand.
Try not to break the hair in two. If you do, get another hair
and try again. Did your hair curl? If not, try again. Be patient;
you'll get the hang of it.
Okay, so this might not be the most efficient
way to style your hair. But this activity wouldn't be possible
if it weren't for the way the cuticle of a hair is structured.
Your cuticle is made of overlapping cells arranged like the
tiles on a terra-cotta roof.
When you run your fingernails across a hair
strand, you pull apart the overlapping cells on one side of
the cuticle more than you pull apart the cells on the opposite
side. The result: a tiny hair that kinks, twists, and curls.
What
are Hygrometers? | How
to Calibrate a Hygrometer | Hair
Hygrometer | Recording
Hygrometer | The
use of The Hygrometer |
