Atg Logo Vector

September Engineering Activity: Slime Chemistry

Have you ever wondered why slime behaves the way it does? It all has to do with chemistry. Follow the steps below to create your own slime at home!
September Engineering Activity: Slime Chemistry - Slime
[social_warfare]

Chemistry is the study of matter, which is the stuff that everything around you is made of. Chemists and chemical engineers 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.

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.”

A Day in the life of a Chemical Engineer: Marina Venezia -
Figure 1

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. You might wonder if it matters how much borax you add to the glue. Changing the recipe can change the properties of the slime!

In engineering, a property is something about a material that you can observe and measure, for example its weight, color, or stickiness. You will make slime with different amounts of contact lens solution, then test the slime and observe how its properties change as the recipe changes. Once you have tested all your slime recipes, you can decide for yourself which one results in slime that will be the most fun to play with.

Materials

  • Washable PVA school glue (like Elmer’s®)
  • Water
  • Baking soda
  • Contact lens solution (must contain both boric acid and sodium borate in ingredients)
  • Food coloring (optional)
  • Measuring spoons
  • Measuring cups
  • Mixing bowl
  • Spatula
  • Ruler
  • Stopwatch
  • Kitchen countertop or other work surface that can get messy
  • Resealable plastic bags or food storage containers
  • Marker
  • Lab Notebook / Data Table

Preparing Your Slime

  1. In the mixing bowl, thoroughly mix 1/2 Cup water, 1/2 Cup glue, and a few drops of food coloring.
  2. Add 1/2 tsp baking soda and mix completely.
  3. Add 1 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 (fold it, squeeze it, and roll it) for 5–10 minutes until its texture stops changing.
  5. Put the slime in a resealable plastic bag or food storage container. Use a marker to label the bag “1 tbsp contact lens solution.”
  6. Clean any residual slime off your mixing bowl and measuring spoons/cups. You should be able to peel the slime off in pieces.
  7. Repeat steps 1–6 two more times, first using 2 tbsp and then 3 tbsp of contact lens solution. When you are done, you should have three batches of slime.

Testing Your Slime

  1. Take your first batch of slime (with 1 tbsp contact lens solution) and play with it with your hands. What does it feel like? Is it stretchy? Squishy? Sticky? Rubbery? Write down your description of the slime in your data table. This is a qualitative observation (it uses things you can describe with your senses, not numbers).
  2. Measure 1 tbsp of your first batch of slime. Since it does not behave like a regular liquid, you will need to mold and squish the slime into the measuring spoon in order to get approximately one tablespoon.
  3. Roll the 1 tbsp of slime into a ball.
  4. Place the ball of slime onto a flat, smooth surface, and immediately start your stopwatch.

September Engineering Activity: Slime Chemistry - Slime

Authors

  • SWE Blog

    SWE Blog provides up-to-date information and news about the Society and how our members are making a difference every day. You’ll find stories about SWE members, engineering, technology, and other STEM-related topics.

  • Heather Sheridan

    Heather Sheridan P.E., PMP is a Civil Engineer and Project Manager at Black & Veatch in the Hydropower Department. Heather has a BS in Civil Engineering from the University of California, Davis with a focus on hydraulic structures and environmental design.

>