Leprechaun Trap Science Project

Green Slime for St. Patrick's Day

Leprechauns love green slime!
Leprechauns love green slime! Actually, this slime is non-sticky, so your leprechauns will get away safely. Nevit, Creative Commons License

Here's how to make green slime for St. Patrick's Day leprechaun trap. We haven't successfully caught any leprechauns using this recipe yet, but it does make a nice holiday chemistry project for kids!

Leprechaun Trap Slime Materials

  • 4-oz bottle school glue gel
  • borax (not boric acid)
  • water
  • green food coloring

Make the Leprechaun Trap Slime Solutions

The leprechaun trap is made by mixing two solutions together, which cross-link or polymerize to make a gel or slime. First, make the solutions:

Borax Solution

Take about a half cup of hot water and stir in borax until it stops dissolving. It is fine if the solution is cloudy or if there is undissolved solid at the bottom of the container. Just add the liquid part to your slime recipe.

Glue Solution

You can make either opaque slime or translucent slime, depending on the type of glue you use for this project. White glue produces an opaque slime. Clear or translucent blue glue will produce a translucent slime. You can color either type of slime using food coloring.

  • Stir 4-oz of glue into 1 cup of water.
  • Add a couple of drops of food coloring. The radioactive chemistry green-yellow color is obtained by adding 2 drops of yellow or 2 drops yellow and 1 drop of green coloring, depending how green you want the slime. For a leprechaun trap, you can add a few drops of green food coloring and call it good. If you're a rebel, dye the slime blue! Blue was the traditional Irish color before green came into vogue.

Make the Leprechaun Trap

Simply mix together 1/3 cup of the borax solution and 1 cup of the glue solution. You can use your hands or you can use a spoon.

Glowing Leprechaun Trap

What leprechaun wouldn't be attracted to a glowing trap? You can make the slime glow very brightly under ultraviolet or light if you add a little yellow highlighter ink to either of the solutions. Highlighter ink is fluorescent, so it emits light when exposed to high-energy light. Note adding the contents of a glow stick will not work, because the other chemicals in the slime will interfere with the reaction that produces the glow.

Cleaning Up the Leprechaun Trap

Although regular slime doesn't stain most surface, the food coloring you added to make it green will stain clothing, furniture, and counters. You can remove the color from countertops using cleaner with bleach. Except for the food coloring, slime washes away with soap and water or in regular laundry.

After St. Patrick's Day

Your leprechaun trap won't last until St. Patrick's Day next year, but if you seal it in a covered bowl or a plastic bag, it will be good for several days. You can extend this to a couple of weeks if you store the bag in the refrigerator. The sealed bag keeps the slime from drying out while the refrigerator keeps it from developing mold.

How Leprechaun Trap Slime Works

When you mix the glue and the borax the polymer in the glue, polyvinyl acetate, undergoes a chemical reaction. Cross-linking bonds are formed, causing the glue stick less to your hands or spoon and more to itself. Feel free to experiment with the amount of glue, water, and borax that you use to make the slime. You can adjust the recipe to make the slime more fluid or more stiff. The molecules in the polymer are not fixed in place, so you can stretch the slime quite far before it will break or tear.

More St. Patrick's Day Science Projects