What Makes Slime Thick: The Secret Recipe

Slime has become a popular toy among kids and adults alike in recent years. The colorful and gooey substance is often made at home using simple ingredients like glue, water, and borax. However, the thickness and consistency of slime can vary greatly depending on the recipe used. In this article, we’ll take a closer look at what makes slime thick and explore the secret recipe behind its unique texture.

Understanding the Science of Slime

Slime is a polymer, which means it is made up of long chains of molecules. When the glue and borax are mixed together, a chemical reaction occurs, causing the polymer strands in the glue to crosslink and form a larger, more complex network. This process is called polymerization and it is what gives slime its characteristic stretchy and rubbery texture.

The Role of Borax

Borax plays a crucial role in making slime thick. It works as a cross-linking agent, which means it bonds the polymer strands together, creating a three-dimensional network. The more borax that is added to the mixture, the more cross-links are formed and the thicker and stiffer the slime becomes.

The Importance of Glue

Glue is the key ingredient in any slime recipe. It is what provides the polymer strands needed to create the slime. The type of glue used can also have an impact on the thickness of the slime. For example, clear glue may create a firmer and more rubbery texture compared to white glue.

The Secret Recipe for Thick Slime

If you want to make thick slime at home, you’ll need the right ingredients in the right proportions. Here is a recipe for making thick slime:

Ingredients Amount
White school glue 1 cup
Borax 1 teaspoon
Warm water 1/2 cup
Food coloring (optional) A few drops
  • Mix 1 cup of white school glue and 1/2 cup of warm water in a bowl.
  • Stir in a few drops of food coloring (if desired) until the mixture is evenly colored.
  • In a separate bowl, dissolve 1 teaspoon of borax in 1/2 cup of warm water.
  • Slowly pour the borax mixture into the glue mixture, stirring constantly.
  • Continue stirring until the mixture forms a ball and becomes less sticky.
  • Knead the slime with your hands until it reaches the desired thickness and consistency.

It’s important to note that the amount of borax used in this recipe can be adjusted to create different consistencies of slime. If you want thicker slime, simply increase the amount of borax used by a small amount until you achieve the desired texture.

Tips for Making Thick Slime

Here are a few additional tips to keep in mind when making thick slime:

  • Use a thick and sturdy mixing bowl to prevent the slime from sticking to the sides.
  • Stir the mixture constantly while pouring in the borax to prevent clumps from forming.
  • Knead the slime with your hands after it has formed to remove any excess water and create a more consistent texture.
  • Store the slime in an airtight container to prevent it from drying out or losing its thickness.


Here are some common questions and answers related to what makes slime thick:

  • What makes slime thick? The thickness of slime is determined by the amount of cross-linking that occurs between the polymer strands. This is achieved through the use of a cross-linking agent such as borax.
  • What kind of glue makes thicker slime? Clear glue may create a firmer and more rubbery texture compared to white glue, which can result in a thicker slime.
  • Can you use too much borax when making slime? Yes, using too much borax can cause the slime to become too firm and difficult to stretch. It’s best to start with a small amount of borax and add more gradually until you achieve the desired texture.
  • Can you make slime thicker after it has already been made? Yes, you can make slime thicker by adding more borax to the mixture and kneading it thoroughly with your hands to evenly distribute the borax.


Now that you know the secret recipe for making thick slime, you can create your own colorful and gooey toys at home. Remember to experiment with different amounts of borax to find the perfect consistency for you. With a little bit of practice, you’ll be a slime-making pro in no time!


  1. Martin, N. (2019). The Ultimate Guide to Making Slime: 101 Recipes with Borax, Glue, Powder, and More! Hatherleigh Press.
  2. Cariaso, T. (2017). The Big Book of Slime: The Ultimate Guide to Stretching Your Imagination and Making a Variety of Slimes. Skyhorse Publishing.

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