Make Guar Gum Slime
Guar gum is a natural polymer found in guar seeds. It is a legume cultivated in India as livestock feed; however, it is also used as food additive and can be found in health food stores.
The long molecules of guar gum can be cross-linked to form slimy/elastic or rubbery substances.
Those of you who like this experiment can order a Slime Science Set that contain guar gum and other chemicals you will need for your slime experiments. With the chemicals you recreive in a kit, you can make many new and interesting products such as soft slime, Flip-Flop Slime, Power Putty, Glooze, and Wiggly Wonder. Teachers and Science Camps can buy larger quantities of Guar Gum at ChemicalStore.com. One pound of guar gum can produce up to 100 lbs of slime.
In this project you will mix a 4% solution of Guar gum with a 4% solution of borax to make slime.
It is exciting for students to see how two liquids can mix and form a slimy or rubbery substance.
Guar gum Slime
This produces a good slime, but is tricky to make, and guar gum must be purchased from a chemical supplier.
The guar solution is made by adding a measure of guar gum to distilled water and stirring to dissolve. It will thicken more if you bring it to a simmer for a few minutes. Skim off the scum that forms on top and allow to cool.
The Borax solution should be 4% , as with the above slimes. Of all the slime recipes I have collected over the years, none vary so widely in concentrations and proportions as those involving guar gum. Typically, the guar is in 1% to 6% solution (though I have seen it up to 12%), and the ratios of guar to Borax solutions range from 10:1 up to 35:1. Start with a Borax solution of 4%, a guar gum solution of 5% and a mix ratio of 20:1 (guar to Borax). Experiment with the guar solution concentration as well as the ratio that the two concentrations are mixed together until you get the consistency you want.
To mix, pour the guar gum solution in a bowl (preferably glass; not plastic), add coloring if you so desire (a few of drops of food coloring works,) and then add the Borax solution. Stir. Guar gum slime improves with age, so let it sit a couple of days for it to be at its peak sliminess. If some happens to get in the carpet, try cleaning with a little vinegar, followed by water.
- Introduction
Curiosity often overwhelms those who see an unrecognizable substance. “What is it?” they wonder, “What can it be?”
Capture your students’ attention with this “goopy” slime recipe.
Concepts
• Polymers, polymerization
Materials
- Guar gum, 10 grams
- 10-mL Graduated Cylinder (or one table spoon measuring spoon)
- Sodium borate solution, 4%, Na2B4O7, 10 mL or one table spoon
- 250-mL Graduated Cylinder or one measuring cup
- Water (distilled or deionized water is recomended, but tap water works as well)
- Food coloring (optional), 1–2 drops
- Stirring rod (or a regular spoon)
Safety Precautions
Slime is generally considered nonhazardous; however, it should not be ingested and should only be used in the manner intended. It is not recommended that students be allowed to take slime home. Slime will easily stain clothing, upholstery, and wood surfaces. With food coloring added, it will stain these surfaces and skin even more readily. Wear chemical splash goggles, chemical-resistant gloves, and a chemical-resistant apron.
Procedure
Step 1: Make a 1% solution of guar gum.
Add 4 cups (or about one liter) water to a steel pot. If desired, add a few drops of food coloring to the water and stir.
Slowly and with constant stirring, add 10 g of guar gum to the water. Note: If the guar gum is added too quickly, it will form large, undesirable clumps. Stir until dissolved. The mixture will thicken slightly within 1–2 minutes. (Optionally you may use a household blender for mixing)
Step 2: Make a 4% solution of borax (Skip this step if you already have a 4% Borax solution)
The Slime Science Set includes 25 grams of borax (BORAX10). Dissolve the entire 25 grams of borax in 600 ml (about 2.5 cups) of warm or hot water. Stir it until fully dissolved and the solution becomes clear. Let it cool down and then store in a clean bottle or jar and label it as 4% Borax Solution. (This borax solution is enough for many slime experiments. Use it for PVA slime, Guar gum slime and many others. A few teaspoons of this solution is usually enough for one cup of slime)
Step 3: Make Guar Gum Slime
Add one cup of guar gum solution (from step 1) to a small bowl and add one table spoon Bprax solution (from step 2). Stir. The mixture should gel and form slime in 1–2 minutes.
Disposal:
Slime can be disposed of with regular household garbage unless otherwise is regulated by your local, state or federal government. review all federal, state and local regulations that may apply, before proceeding.
Tips
• Try using distilled or deionized water. The ions present in tap water may interfere with the polymerization reaction, causing the slime to turn watery after only an hour or two. Slime made with distilled or deionized water will retain its properties and consistency for several days.
• Store the slime in an airtight container or bag to prevent it from drying out.
Discussion
Guar gum, a natural polymer with a molecular weight of about 220,000 g/mole, is made from the ground endosperms of Cyamopsis tetragonolobus, a legume cultivated in India as livestock feed. Guar gum has 5–8 times the thickening power of starch and is commonly used as a binding or thickening agent in foods and cosmetics.
Guar gum is a long-chain polyalcohol with 1,2-diol groupings capable of complexation with the borate ion, B(OH)4–. The structures given below are oversimplified, but may help to visualize the network complex as it extends in three dimensions.
In addition to forming complexes with the borate ion, the interaction of long-chain polyalcohols, such as guar gum, with the borate ion leads to cross-linking of different polymer chains, or sometimes part of the same chain, in such a way that a three-dimensional network of connected chains is formed. When the concentration of cross-linked chains is high, solvent is immobilized within the network and a semisolid gel results. Because the borate ion can bond with four alcohol groups it is particularly effective in creating three-dimensional gel networks from gums such as guar gum.
Other examples of networks and gels are rubber cement, gelatin, fruit jellies, agar, and yogurt.
After you make your slime, you may place it in a bag for future use or display at the science fair. A plastic bag can keep your slime fresh and protect it from drying out.
