Rubbery Flubbery Fun

    Kids, this is a procedure for making the non-sticky sort of rubber, or gelatinous slime, that is known as “flubber”. It is a completely safe substance that is not sticky and is non-toxic. You will need an adult partner for handling the heating steps. 

    Please note:  All chemicals and experiments can entail an element of risk, and no experiments should be performed without proper adult supervision.


    1. Mix 1 teaspoon of a soluble fiber powder (such as Metamucil®) with 1 cup (8 ounces) of water in a microwaveable bowl. For coloring you can add a drop or two of food coloring, a little powdered drink mix, or some flavored gelatin.
    2. Place bowl in the microwave and heat on high for 4-5 minutes until the goo is about to bubble out of the bowl. Turn off the microwave.
    3. Let the mixture cool slightly, then repeat step 2. The more times this step is repeated the more rubbery your substance will become.
    4. After 5-6 microwave runs, (carefully - hot hot HOT) have your adult partner pour the flubber onto a plate or cookie sheet. A spoon can be used to spread it out.
    5. Allow to cool. You now have some non-stick flubber! A knife or cookie cutters may be used to cut the flubber into interesting shapes.
    6. Flubber can be stored at room temperature in a sealed baggie for several months. It will last indefinitely in a sealed bag in the refrigerator.

    Tip: If the flubber is sticky then the amount of water needs to be reduced. It should be clammy, but not sticky. Use less water next time.

    What’s the science?

    Flubber is a polymer. Polymers are large molecules consisting of repeating identical structural units connected by covalent chemical bonds. Polymers can be naturally occurring or manmade. Manmade polymers are materials like nylon, polyester, and polystyrene. Examples of naturally occurring polymers are proteins in our body like tubulin and actin. The polymer in Metamucil is natural psyllium fiber – a type of polysaccharide. “Soluble” means that it will dissolve in a lot of water, but once the water evaporates the fibers become more and more entangled, forming our gelatinous “goo”.


    Kathleen Carrado Gregar, PhD, Argonne National Labs 
    [email protected]
    February 2010


    Anne Marie Helmenstine’s website at: and
    The Science Café at