A Jelly Good Glow!

Posted by: on Nov 25, 2012 | No Comments

Halloween’s gone for another year but here’s one more UV light / ‘glow in the dark’ idea to share with you. It’s easy to make Jelly or other gelatin glow under a black light for parties or any occasion. Here’s what you do.

You will need

A packet of jelly

Tonic water

UV lamp (also known as a black light)



To make the jelly you basically just follow the directions on the packet, except you use tonic water instead of water. For a small packet, the usual directions would be to heat approx 250 ml of tonic water to boiling point. Mix the boiling tonic water and jelly until the powder is completely dissolved.


Stir in another 250 ml of tonic water.

Pour the liquid into a pan or bowl.


Refrigerate the jelly until is has set.

You can use cookie cutters to make shapes out of the jelly, if desired.

Shine a UV lamp (or black light) on the jelly to make it glow.


What’s Happening?


No matter what flavour or colour of jelly you use, it will glow bright blue under the black light. This is the fluorescence of the quinine in the tonic water.

Quinine also gives tonic water a distinctive bitter flavour which you will also taste in the gelatin. If you don’t like the taste you can lessen it by using half tonic water and half tap water in the recipe. Either sugar-free or regular tonic water works fine for this recipe. Have Fun!


Bonus Science

Source of Gelatin. Most of us have heard that gelatin comes from cow horns and hooves, and it sometimes does, but most of the collagen (naturally occurring protein) in the gelatin comes from pig and cow skin and bones. These animal products are ground up and treated with acids or bases to release the collagen. The mixture is boiled and the top layer of gelatin is skimmed off the surface.


From Gelatin Powder to Jelly. When you dissolve the jelly powder in hot water, you break the weak bonds that hold the collagen protein chains together. Each chain is a triple-helix that will float around in the bowl until the gelatin cools and new bonds form between the amino acids in the protein. Flavoured and coloured water fills in the spaces between the polymer chains, becoming trapped as the bonds become more secure. Jelly is mostly water, but the liquid is trapped in the chains so jelly jiggles when you shake it. If you heat the jelly, you will break the bonds that hold the protein chains together, liquefying the gelatin again.


Thanks to, and adapted from about.comguide