Here's a great activity that I found on Putti Prapancha's blog.
-Paintbrush and/or medicine dropper
-Colored water (we used about a tablespoon of water with 6-7 drops of food coloring)
-Little bowls for colored water
Have your child draw a picture with glue.
Then sprinkle the glue with salt. We did this on top of a piece of cardboard, but a baking sheet will work well too.
Next have your child take a paintbrush or a medicine dropper and drop colored water, one drop at a time onto the salt.
Your kids will be amazed to see the salt absorb the food coloring.You can't see the paint brush in this picture...but this was a smile that flashed across my sons face after he did his first dab of food coloring to the salt. He just loved how the color started traveling through the salt.
This is how his face was for the remainder of the time he spent doing this activity. He was intently watching how the colors traveled. He spent about a half hour doing this activity...making six drawings during that time.
Some tips: Make sure they lightly touch the salt with the brush. It also helps to have a bowl to clean the brush in between colors...otherwise you lose the colors start blending together and you lose the vibrant colors because they become murky.
We also tried using a medicine dropper. This worked well too, as long as the child is able to have good control over how much colored water comes out. At times my son squirted too much and the colors pooled onto the drawing.
Please also note that this painting activity is just for fun...even though you glued the salt to the paper...it doesn't actually stick and won't last.