Separating Colors

Leave it to science to prove me wrong.  Recently, we read a few color mixing themed books and, of course, we mixed colors after reading them.  We mixed with paint and play dough.  After telling my kids that we could not separate colors once they are mixed together, I found a few science experiments that do just that!  We still can't separate the colors from the paint or play dough that we mixed, but it was fun to try these science experiments.  This is the most successful of the experiments we tried:

Materials needed:
-yellow, red, and blue food coloring
-a bowl for mixing the food coloring (and something to mix it with)
-glass jar
-coffee filter
-paint brush
-pencil
-paper clip
-water

For the experiment, we put a drop each of red, yellow, and blue food coloring in a bowl and mixed them together.  We observed the color of the mixture - black.  Then we cut a strip of a coffee filter a little longer than the jar we used and put a dot of the mixed colors about one inch up from the bottom of the strip (we used a paintbrush to do this).

Next we secured the top of the strip around a pencil with a paper clip and added about a 1/2 inch of water to the jar.

We dangled the strip in the jar so the bottom of the strip just touched the water.  The water traveled up the paper and amazingly, when it reached the dot, the colors separated.

It was difficult to capture this in a picture, but you can kind of see the red and blue, and a thin streak of yellow in between the red and blue.  According to the book we used, different pigment molecules travel at different speeds and that is why you see separate paths of color.  I was much more interested in this than C and R were, and it took four tries to get this to happen.  The first time I didn't read the directions correctly (great teacher I am!), the second time someone knocked over the jar and water spilled all over our materials, the third time there was crying for some reason so we stopped, and finally (I can't believe I didn't give up before the fourth try) we got results with the fourth try. 

Speaking of the book, the title is Super Science Concoctions by Jill Frankel Hauser.  I recently saw this book mentioned on the Almost Unschoolers blog.  We are hoping to try a few more experiments from this book before returning it to the library.

I am linking this to Science Sunday at Adventures in Mommydom.  Visit that blog for more science fun.