Design Your Own Slime

Abstract

There are many different kinds of slime out there. Some slime is runny and liquid-like; other slime is thick and rubbery. Some slime glows in the dark, some is fluffy, and some is even magnetic! What set of properties makes the best slime? What kind of slime would you choose to make if you were selling slime as a toy in your own "slime shop"? In this project, you will experiment with different slime recipes and try to perfect one to make slime with the exact properties you want!

Summary

Areas of Science

Chemistry

Difficulty

Method

Engineering Design Process

Time Required

Very Short (≤ 1 day)

Prerequisites

None

Material Availability

Readily available

Cost

Very Low (under $20)

Safety

Supervision required for small children. The slime is not edible.

Credits

Ben Finio, PhD, Science Buddies

Science Buddies is committed to creating content authored by scientists and educators. Learn more about our process and how we use AI.

https://www.youtube.com/watch?v=bcfzUOdM8lg

Objective

Define desired properties for your slime, and then find the recipe that gives the best results.

Introduction

If you have ever played with slime, you know that it can be fun with all of its stretchy, bouncy, ickiness. Maybe you have noticed that some types of slime feel different than others. Have you ever wondered why slime behaves the way it does? It all has to do with chemistry. Chemistry is the study of matter, which is the stuff that everything around you is made of. Chemists are interested in finding out what different materials, such as slime, are made of, how these materials behave, and how they can be changed into other materials.

What is slime actually made of? If you have made slime before, you probably followed a recipe to put different ingredients together, similar to baking a cake. The ingredients used for slime usually include Elmer's® glue and borax. Elmer's glue is made up of a polymer. Polymers are long chain-shaped molecules.

The polymer chains in the Elmer's glue are long and very straight. The polymer chains can slide across each other easily, making the glue runny and "liquidy" (think of dumping a bunch of fresh-cooked spaghetti out of a pot). This changes, however, when you mix the glue with borax. The borax helps make connections between each of the polymer chains, as shown in Figure 1. This process is called crosslinking. This makes it harder for the polymer chains to slide around, making the glue thicker and turning it into "slime." In this project, you will use contact lens solution to make slime. It contains other ingredients (boric acid and sodium borate) that react with baking soda (another ingredient in your slime) to make borax.

Image Credit: Ben Finio, Science Buddies / Science Buddies

Figure 1. Straight polymer chains (left) are linked together by borax to form a cross-linked polymer (right).

You might wonder if changing the recipe changes the properties of the slime. In science, a property is something about a material that you can observe and measure, for example, its weight, density (mass per unit volume), color, stickiness, or viscosity (how easily the slime flows). There are many different types of slime with different properties. Some slime is thin and runny; some slime is thick and rubbery. You can add extra ingredients to slime to make it sparkly, magnetic, or glow-in-the-dark. Figure 2 shows just a few examples of what your slime could look like!

Image Credit: Ben Finio / Science Buddies

Figure 2. Different types of slime. Clockwise from the top left: "regular" slime, magnetic slime, thermochromatic slime, and glow in the dark slime.

Terms and Concepts

• Chemistry
• Matter
• Polymer
• Crosslinking
• Properties
• Density
• Viscosity

Questions

• If you could make any slime you wanted, what properties would you want it to have?
• What ingredients do you think you would need to give your slime those properties?
• Search online for slime recipes. What types of slime do you find recipes for?

Materials and Equipment

This is an engineering design project, the exact list of materials you need may vary slightly. To make a typical basic slime recipe, you will need:

• Washable PVA school glue (like Elmer's®)
• Water
• Baking soda
• Contact lens solution. Must contain both boric acid and sodium borate. Make sure to read the ingredients list, especially if purchasing online.
• Food coloring
• Measuring spoons
• Measuring cup
• Large mixing bowl (at least 4 quarts recommended)
• Spatula
• Resealable plastic bags or food storage containers
• Optional, depending on the type of slime you plan to make and the tests you plan to do (see procedure):
  • Disposable gloves for handling/mixing slime
  • Digital scale
  • Ruler for measurements (bounciness, stretchiness, viscosity, etc.)
  • Timer for measuring viscosity
  • Black light

You can also try various additives to change the properties of your slime. 

• Glitter (sparkly slime). Note: use biodegradeable glitter for your project to have less of an impact on the environment. Glitter is also available in different shapes.
• Iron filings (magnetic slime). Note: magnetic slime may eventually become discolored as the iron filings rust.
• Fluorescent pigment, paint, or powder (glow-in-the-dark slime)
• Thermochromic pigment (color-changing slime). Note: this pigment may require a large temperature change, like putting an ice cube in the slime or repeatedly kneading it with your hands, to produce an effect. 
• Tonic water (glow-in-black-light slime)
• Foam shaving cream (fluffy slime). Note: requires a larger mixing bowl due to the large volume of shaving cream.

This project follows the Engineering Design Process. Confirm with your teacher if this is acceptable for your project, and review the steps before you begin.

1. Think about how you will evaluate your slime's properties. Some of the properties and observations may be qualitative (for example, you want the slime to be sparkly, and you can determine how sparkly it is by looking at it). Some properties can be measured quantitatively. Table 1 gives some examples of quantitative properties you can measure for a basic slime recipe.
   Swipe left to see more

   Table 1. Examples of quantitative measurements.

   Property	Measurement
   Apperance	Qualitatively describe what the slime looks like
   Mass	Measure the mass of a certain volume of slime
   Bounciness	Drop a ball of the slime next to a ruler and measure how high the slime bounces
   Stickiness	Evaluate how much the slime sticks to your hands after handling it
   Stretchiness	Measure how far you can stretch a fixed volume of the slime at a fixed rate before it breaks
   Viscosity	Place a ball of slime on a flat surface and measure how quickly it spreads out to a circle of a certain diameter

2. If you decide to make a "special" type of slime, you may need to add more properties. For example:
   1. How quickly does your thermochromic slime change color if you drop an ice cube into it? What color does it become?
   2. From how far away can you attract magnetic slime with a magnet?

3. After you have decided what properties you will evaluate, make a data table like Table 2 to record results for your different recipes.

   Swipe left to see more

   Table 2. Example data table.

   Slime Batch #	Recipe	Appearance	Mass	Bounciness	Stickiness	Stretchiness	Viscosity
   1
   2
   3
   ...

4. Watch the video to learn how to make a basic slime recipe. The video is available in Spanish too.
   

   https://www.youtube.com/watch?v=bcfzUOdM8lg
   1. In a mixing bowl, thoroughly mix 1/2 C water, 1/2 C glue, and a few drops of food coloring.
   2. Add 1/2 tsp baking soda and mix completely.
   3. Add 2 tbsp contact lens solution and stir vigorously until the mixture starts pulling away from the edges of the bowl.
   4. Use your hands to knead the slime for 5–10 minutes until its texture stops changing. Do not worry if the slime is very runny and sticks to your hands at first (you can always wear disposable gloves if you do not like the feeling of slime sticking to your hands). It will continue to get thicker as you knead it. It gets easier to clean up the slime as you knead it more!
5. Evaluate the basic slime recipe using the properties defined in Table 1, along with any additional properties you select. Note that it is important to be consistent with how you test your slime. Here are just a few examples:
   1. For measuring mass, always measure the same volume of slime first (for example, 1/2 C). Optionally, you can calculate density (mass per unit volume), but you will want to convert your volume units to metric first (mL or cm³).
   2. For dropping a ball of slime to measure bounciness, make sure you always drop a ball of the same size (same volume).
   3. For measuring stretchiness, make sure you always pull a same size (same volume) ball of slime apart at the same speed. The slime may break sooner if you yank on it more quickly. Figure 3 shows an example stretch test.

Image Credit: Ben Finio / Science Buddies

Figure 3. Example slime stretch test done by pulling on the slime at a constant rate until it breaks and measuring the total length.

6. If you have not already, do your own research online about slime recipes and different types of slime.
7. Define criteria for your slime's properties. For example:
   1. What should your slime look like?
   2. What should your slime feel like?
   3. How thick should your slime be?
   4. How heavy should your slime be (dense and heavy or light and fluffy)?
   5. Should your slime have any special properties (magnetic, glow-in-the-dark, etc.)?
8. Based on your background research, write down a recipe that you think will result in slime with these properties.
9. Add any additional columns you might need to your data table for slime with special properties, like magnetism or thermochromism (color-changing with temperature).
10. Follow the recipe to make the slime. When you are done, measure your slime's properties and record them Table 2.
11. Do your slime's properties exactly match the criteria you defined in step 6? If not, now it is time to iterate. This is an important part of the engineering design process. You may need to make changes to your slime recipe, try again, and evaluate how the properties changed.
    1. In general, it is important to only change one thing at a time. If you change two ingredients at once, you might not be able to tell which one resulted in a property change.
    2. If your recipe did not work at all, or came out very different from how you expected, you may need to go "back to the drawing board" or make more dramatic changes.
12. Make changes to your recipe based on your observations and knowledge of what different ingredients contribute to the slime (for example, using more contact lens solution should make the slime thicker). Follow your new recipe to make another batch of slime and evaluate its properties.
13. Keep iterating and testing new slime recipes until you have found a recipe that gives you slime with all the desired properties.
14. Store each batch of slime in a separate, airtight container for future use. If you want to dispose of your slime, put it in the trash. Do not try to pour slime down the drain, or it will cause a clog.

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