Glowing Oobleck – An Easy Slime Recipe

Glowing oobleck is an easy, two-ingredient slime recipe that’s perfect for Halloween or exploring with a black light. Make regular oobleck, glowing oobleck, and glow in the dark oobleck. Then, have fun layering the 3 types together creating designs as you play.

Glowing Oobleck - an easy slime recipe

Glowing Oobleck


  • cornstarch
  • tonic water {that says contains quinine}
  • black light {UV light source}
  • tap water {optional}
  • glow in the dark paint {optional}

How to Play:

glowing oobleck invitation

  1. Add some cornstarch to a bowl. Start with about a 1/2 cup.
  2. Slowly add tonic water to the bowl – a spoonful at a time would be helpful. I let Aiden be in charge and he added a bit too much. Our cornstarch just dissolved in the water.
    making oobleck
    If you add just a little of water at a time, you can experience how the the mixture changes texture. The cornstarch starts fluffy soft. Adding a little water makes it feel like a squishy solid. Adding a bit more water {somewhere around a 1:1 ratio} makes it oobleck. Adding too much water dissolves the cornstarch and makes a slurry for gravy.
  3. If you add too much tonic water, add more cornstarch. Keep adjusting the amounts of cornstarch and water until you get the slime consistency you desire.

When you move through the cornstarch and water mixture slowly, it will feel like slimy liquid.  If you tap hard on the mixture, it will act like a solid.  {Oobleck is a non-Newtonian fluid.}  Pick it up, bounce it around in your had, treat it like play dough, and then let it ooze down.

How to Make it Glow:

Tonic water has quinine in it which fluoresces under UV light {a black light}. Here’s what it looks like by itself {with no cornstarch}.

glowing tonic water

Go to a dimly lit or darkened room. Hold a black light over the bowl of cornstarch and tonic water. You’ll see the oobleck glow blue. Explore the mixture and have fun watching it glow.

glowing oobleck1

Add to the Fun:

Mix up a small amount of oobleck using cornstarch and tap water. This oobleck will not fluoresce under the black light. Drizzle the regular oobleck onto the top of the glowing oobleck.

glowing oobleck2

Enjoy making cool designs. Mix up the glowing oobleck to start over.

glowing oobleck3

Aiden’s assessment: “This is so cool!”

Glow in the Dark Oobleck

glow in the dark oobleck

If you add some glow in the dark paint to some regular oobleck, you can get 3 layers of cool designs. The glow in the dark paint phosphoresces when exposed to light and it’s even brighter under UV light.

glowing oobleck4

Science Note

The difference between fluoresce and phosphoresce: fluorescent materials glow in the present of a radiation source {in this case the black light}. When you turn off the light, they no longer glow. Phosphorescent materials glow in the present of a radiation source {sunlight, incandescent light, or UV light in the case of glow in the dark paint} and continue to glow for sometime after the light source is removed.

More Glowing Halloween Science Fun


This post was originally published on October 18, 2014.

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