Drawing realistic hair can be time consuming. But if you take the
time to do it right, it will add a ton of realism to your penicl
portrait.Women's Hair:
Let's start with women's hair. The first
thing you need to do is draw an accurate outline. Use the grid technique to get
the proportion correct.

Use a pencil to add the darker Full and 3/4 tones. Check your original
reference photo to see where to place each tone. Also, keep in mind the
direction of the hair.

Now, we are going to use the "dirty eraser" trick to blend the tones you just
added. Take a pencil and a piece of scrap paper. Scribble a very dark area of
graphite onto the scrap paper. Using a sharp edged eraser (the kind that erases
pencil on one end and ink on the other), rub the "ink" end onto the scribble.
The eraser will pick up the graphite.
Begin to blend the dark tones in the
hair by "dragging" the sharp edge of the dirty eraser over the tones. As you do
this, the graphite will come of the eraser. It will naturally add some lighter
lines. This will add some highlights to the hair.
With the eraser, drag the
darker tones into the lighter areas. Likewise, drag the lighter areas into the
dark. You can switch to the "pencil end" (the white end) of the eraser to add
even more highlights. Check your original photo to see where.
Now take a
tortillon and smooth everything. Make sure everything blends together smoothly
and naturally.

Here's an example of a woman with short hair. The steps are the
same.
Start
With An Accurate Outline
Add the darker
tones with your pencil
Shade and
Blend
When you are drawing hair, build layer after layer until you get the fullness
you need. To do that, just repeat the steps over and over a few times. This
will build layers to the hair and make it look more natural.
Men's Hair:
The steps are the same for drawing men's hair. Start with
an accurate outline using the grid.

Reffering to your original photo, add the darker tones with the pencil in the
direction of the hair.

Using a combination of the sharp edged(dirty)eraser and the tortillon, build layers
to the hair until you get the fullness you need.

African American
Hair:
This is just a little variation of the same technique. Begin again
with an accurate outline.

This time, use a sharp
pencil to add tight, little circles to the hair. Keep the circles close.
Overlap them.

Use a
tortillon to blend the circles together. Roll the end of a kneaded eraser into
a point. Dab around the hair to add some highlights. Continue this over and
over until you get the fullness you need.

This is a short
lesson on how to draw realistic hair. For a much more in depth study of drawing
hair, please check out my How To Draw Books.