For New Year’s Eve this year, my family celebrated with dinner with neighbors, and a fun STEAM activity involving coffee filters and capillary action. We watched as color exploded on the coffee filter, creating our own (safe to use inside the house) fireworks. I wanted to use a different kind of coloring agent, so I thought we would try the same experiment, but using watercolors instead. But when the boys painted the coffee filters, the watercolors went straight through the coffee filter! I was reminded by my husband that coffee filters are semipermeable membranes, which is why they are used in filtration to make coffee. Semipermeable membranes allow for some molecules to pass through, and others not. A coffee filter holds back the coffee grounds, but water, flavor, and caffeine pass through the filter into our cups. I had an idea that would allow us to capture our coffee filter paintings through the semipermeable membrane coffee filter.
Semipermeable Membrane Painting STEAM Actvity
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Supplies:
- coffee filter
- watercolor paper
- watercolors
- 5 small plastic paint cups
- pipettes (one for each color, to prevent the paints from mixing)
Coffee Filter Painting
STEP 1: Fill the small plastic paint cups with water, then add watercolors from tubes for desired colors. We chose red, yellow, green, blue, and purple.
STEP 2: Place a coffee filter on top of one sheet of watercolor paper. I also place a wipe-able place mat under the watercolor paper.
STEP 3: Paint the coffee filter using the pipettes and watercolors. Drop one drop of water color at a time, and watch how the paint spreads through the coffee filter.
As I explained in another post, the paint moves due to capillary action. All three of my boys loved this part, and I loved watching them create!
My littlest one decided he wanted to push down all the bubbles that were made when he was dripping paint.
Here’s how their painted coffee filters turned out!
STEP 4: Let the painted coffee filters dry completely.
STEP 5: Once dry, slowly pull the coffee filter away from the water color paper. My boys loved this part too! It was like watching them unwrap a present to see what was under the paper.
Their final creations. So beautiful!
You will notice the paint went completely through the coffee filter, and onto the watercolor paper. That is because the coffee filter is a semipermeable membrane. The filter allows the water, and the color pigment in the paint, to almost completely flow through the coffee filter, and onto the thick, watercolor paper.
Isn’t science beautiful?
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Looking for other STEAM activities for you kids? Check some of my ones!
Easter Egg STEM Activity
Capillary Action Color Explosions!
Make a Rainbow using one of the Properties of Water
Appearing Snowflake: A Winter Activity for Kids
Painting Pumpkins with Paintballs: A Quick STEAM Activity
Paintball Forces Science Experiment