Imagine a piece of yummy chocolate with a smooth surface that shines in all the colors of the rainbow. It’s not make-believe. It’s called iridescent chocolate, or sometimes holographic chocolate, or rainbow chocolate — and you can make it yourself!
This recipe is perfect for parents and teachers, and it makes for a fun (and edible!) science experiment. It takes less than half an hour, and you don’t need any special chemicals to coat the chocolate. This is pure physics and the magic of science at work.
- Teach children about optics, light diffraction, and the nature of color.
- Teach children about crystalline structures in chemistry and how we use them in food.
- Rainbow chocolate is its own reward!
You Need a Color Diffraction Grating
To make your own holographic chocolate, the only special thing you will need is one of our diffraction grating sheets. We recommend this diffraction grating. Or, if you are purchasing for an entire school, we also sell our diffraction grating material by the roll.
Iridescent chocolate works by using the properties of light. Diffraction gratings have microscopic grooves on them that cause the different wavelengths of white light to crash into each other, creating interference patterns. This creates the rainbow effect. It’s the same phenomenon that gives CDs and DVDs their rainbow-colored light. (And, unlike a CD, holographic chocolate is safe to eat.)
Use Tempered Chocolate
You will need to use tempered chocolate for this technique to work. Any plain chocolate bar from the store will do, or you can temper your own.
What is “Tempered” Chocolate?
Chocolate can have different microscopic forms, and the fine crystalline structure of tempered chocolate is necessary for creating the rainbow effect in holographic chocolate.
Tempered chocolate has a great snap that consumers love, so most commercial chocolate is tempered. Just make sure it doesn’t melt and resolidify before you use it, as this will ruin the tempering.
Is a Diffraction Grating Safe to Use on Food?
Yes! The material is non-toxic, and none of it gets into the food. (Don’t put it in the oven, though. It’s not like parchment paper.)
Before making your iridescent chocolate, wash your diffraction grating with soap and water first in order to remove any impurities. Don’t scrub the grating with a sponge or pad. When it’s clean, allow it to air dry rather than using a towel.
Our Favorite Rainbow Chocolate Recipe
Our favorite recipe for holographic chocolate is the one from Popular Science, which has been making science cool for over 150 years.
Their recipe uses a Rainbow Symphony diffraction grating, just like the one we recommended above, so we are very flattered! Making fun educational aids for the study of light and color is one of the original reasons we founded Rainbow Symphony, and it always makes us happy to see our science tools being used in projects like this.
See More Fun Projects on Our Blog
Holographic chocolate is delicious, but it only lasts until you eat it. For some non-edible alternatives that create rainbows for years on end, check out our suncatchers and rainbow decals.
For more projects, educational inspirations, and information about upcoming solar eclipses that you will want to use our popular ISO- and CE-certificatied solar eclipse glasses to safely view, check out our blog.