Exploding Rainbow Milk Spiral

The classic milk, food coloring, and dish soap experiment! This easy science demonstration shows how soap can send colors flying through (2% or whole) milk, and there are lots of examples on YouTube. But this version, an Exploding Colors Milk Spiral, literally puts a twist on it. The secret: A well-positioned line of caulk and a dish soap-soaked string.

The caulk forms a wall that extends halfway across the shallow dish. When the string is placed between that caulk and a row of food color dots, the colors spiral around the dish in the opposite direction. “This video is a variable time-lapse of a reaction that went on for an hour and a half,” YouTuber AutistiVision explains. “You can see when it finally ran out of soap. This was fun!”

So what’s happening? From Sick Science:

The secret of the bursting colors is in the chemistry of that tiny drop of soap. Like other oils, milk fat is a non-polar molecule and that means it doesn’t dissolve in water. When soap is mixed in, however, the non-polar (hydrophobic) portion of micelles (molecular soap structures in solution) break up and collect the non-polar fat molecules.Then the polar surface of the micelle (hydrophilic) connects to a polar water molecule with the fat held inside the soap micelle. Thanks to the soap connection, literally, the non-polar fat can then be carried by the polar water. This is when the fun begins.

AutistiVision tries more caulk configurations in the video below:

Plus, more soap videos and more colorful liquid experiments:
• Van Gogh’s Starry Night painted on dark water
• Odyssey: A universe of ink, oil, soap, and glitter in macro detail
• How to make an Amazing 9 Layer Density Tower
• Guinness World Record Elephant Toothpaste Reaction
• Pacific Light: Water, ink, oil, and soap form a tiny universe of color