Make Bubble Art Valentines

In this simple science activity, kids make a bubble paint "potion" and explore bubbles while making pretty valentines.

Simple explanation:  The bubbles in today's activity are a gas trapped inside a liquid.  (How did the gas get inside the paint solution?)  When the bubbles pop, they leave their liquid outsides behind on the paper.  We can see this clearly because of the paint we added.

More details:

Bubble solutions are usually made up of soap molecules mixed with water.  In this case, we also added paint.  When you blow a bubble, the surface of the bubble is actually made up of three layers: a layer of soap molecules, a layer of water, then another layer of soap molecules.

Bubbles form when water molecules stick together, creating surface tension. When molecules stick together too firmly, bubbles don't form as easily.  That's why when you blow bubbles in water alone, the bubbles don't mound up on top -- they just pop.  But adding soap helps decrease the surface tension, making bubbles easier to form.

Bubbles pop because the water in them evaporates.  Glycerin and other thickening agents have water-holding properties that delay evaporation, making the bubbles last longer.  When you blow bubbles on a rainy day, they last longer because there is more moisture in the air.  What do you think happens on a sunny day?  How about a windy day?

Soap molecules have both a hydrophobic (repels water) and hydrophilic (attracts water) side, the molecules line up with their hydrophobic side facing out to the air and their hydrophilic side facing in toward, and sticking to, the layer of water!

Bubbles are "minimal surface structures" (as are balloons). This means that they always hold the gas inside of them with the least possible surface area – and the shape with the least surface area for any given volume is always a sphere.  This is why bubbles are always round, even when you blow them through a square wand.

We see colors in a bubble through the reflection and the refraction of light waves off the inner and outer surfaces of the bubble wall.   You can't color the bubble itself since its wall is only a few millionths of an inch thick.  Instead, a bubble reflects color from its surroundings.  The thicker the bubble’s walls, the more intense the color.  In this activity, the color left behind on the paper was the paint that was mixed into the water.