Mixing Colors
Have you ever wondered what the world would be like if there were no colors?
What if there were only a few colors? It would probably be a very boring world
compared to the one we live in now. Everyday you are surrounded by many
different colors that come in different shades and hues. These are the results of
color mixing. Today, we are going to learn about two different types of color
mixing: additive color mixing and subtractive color mixing.
Mixing Color Lights
Mixing color light is called additive color
mixing because the combined colors are formed by
adding light from two or more light sources, which
will give more illumination than any of the lights by
themselves. In other words, the brightness of
the lights is added together. For example, adding
green light and blue light produces cyan light,
which is brighter than its two components.
Like in painting, all colors of light can be
made from mixing three primary colors. Do you know the primary colors for light?
In painting, the three primary colors are yellow, blue, and red, but for light they
are RED, GREEN, and BLUE.
Red and green light make yellow light. Green and blue light make cyan light.
Blue and red light make magenta light. What do you think Red + Green + Blue light
make? What is the brightest color of light
Mixing color lights is used in theatre performances to create a dramatic
effect. It is also used in television and computer monitors to create the full range
of colors that give you the colorful cartoons or video games that you see and play.
Mixing Paint
Mixing paint is a kind of subtractive
color mixing because different colors of paint
absorb different colors of light. Any color
that is not absorbed or subtracted from the
light will reflect off the paint. We can only see
the reflected color. For example, cyan paint
alone will subtract red light. Yellow paint alone
will subtract blue light. A mixture of cyan and
yellow paint will then subtract both blue and red light. Because the primary colors
of light are red, blue, and green, we will see the reflected green light if we mix
cyan and yellow paint. Black paint absorbs all light and white paint reflects all light.
Subtractive painting also allows us to see the
difference in shade, such as the difference
between red and dark red. Remember that dark
red paint is made from black and red paint. Black
light absorbs all light so it subtracts green, blue,
and red light. Red paint subtracts only green and
blue light. So, dark red paint will subtract green,
blue, and some red light so will look darker than red
paint alone. Can you explain why if we mix green and white paint, we get a lighter
green?
What do you think the primary colors of mixing paint is? Surprisingly, it is
not the yellow, red, and blue that we expected. It is actually cyan, magenta, and
yellow. Your color printer at home actually uses these three colors to make the
colorful pictures that you print out!
How do you see color?
In our eyes are color receptors that get triggered when a certain light is
reflected into our eyes. These color receptors are called “cones,” and we have
green, red, and blue sensitive cones that help us see colors in this world.
Experiments:
Today, we will be working with subtractive color mixing through mixing paint and
also through mixing colors with the color sensitive cones in your eyes.
Mixing Paint
What you need:
Paper Plate
Paintbrush
Cup with water
Red, Yellow, Blue, White Paint
What you do:
1. Get a some red, yellow, blue, white paint.
2. On a blank spot on your plate, add a little Red paint to Yellow Paint. What
color do you get? (Make sure to use the water to clean your paint brush so
you don’t get other colors on your stock colors)
3. On another blank spot, mix a little of Red and Blue paint. What color do you
get?
4. Now mix a little of Blue and Yellow. What do you get?
5. Mix all three together. What color do you expect to get? Can you explain
why you get this color?
6. Now mix some white to one of your colors. What happens? Why?
7. Try to make your favorite color with the given colors.
Mixing Colors With Your Eyes
What you need:
CD with a penny
Paper
Scissor
Crayons/Markers
What you do:
1. Take the paper and cut out a circle as big as the CD.
2. Divide the circle into 8 sections by straight lines from the edge through the
center of the circle.
3. Choose two colors and color in the eight sections in alternating order.
4. After you are done coloring, cut a small slit in the center of the circle big
enough to fit in the penny on the CD.
5.
6.
7.
8.
Slide the paper onto the CD with the penny.
Spin the CD. What do you see?
Now try it with two different colors. What do you expect to see?
Now try it with three different colors. What do you expect to see?
Benham’s Disc
Now, let’s try something really cool. This pattern is called the Benham’s Disc and
only uses black and white colors. Cut it out and cut a small slit in the center to fit
it onto the CD with a penny and spin it. What do you see?
Unfortunately, scientists are still trying to explain this phenomena. No one really
knows why we see the colors that we do, but it shows how color mixing is really cool!
Questions
1. What are the three primary colors in the additive color mixing system? What
are the three primary colors in the subtractive color mixing system?
2. Why do you make black if you mix all the paint?
3. Why do colors become lighter if you add white paint and darker if you add black
paint?
4. What are the color sensitive receptors in our eyes?