How can I make slime?
Learn how to make Gak—a slime that has both liquid and solid
properties.
Setting: Indoors
Time: < 30 minutes
Concepts: polymers, elasticity
Skills: predicting, observing
Subject(s):
 Chemistry
Ages:
 6-8
 9-11
Materials:
 Sodium borate (Borax) detergent
 Warm water
 Food colouring (optional)
 White school glue
 Measuring cups (1/4 c. and 1/2 c.)
 Measuring spoons (tbsp.)
 Small plastic zip bag
Safety First!
 Be careful working with hot water. Adults, provide assistance for young
children when using hot water.
 The slime is non-toxic but it is not food! Do not put Gak in your mouth. Keep
it away from small children and pets.
What to do!
1. Mix 1 cup of warm water with 1 tablespoon of sodium borate (Borax). Stir until the
powder has dissolved.
2. Mix together 1/4 cup of white school glue with 1/4 cup of warm water.
3. In a plastic bag, mix 1/2 cup of the glue solution with 1/2 cup of the sodium borate
solution. Add a couple drops of food colouring (optional).
4. Seal the plastic bag and knead the mixture until it becomes a ‘tacky’ consistency.
5. Dig in and have fun! Does it bounce? Does it stretch? Is it a liquid or a solid?
6. Store in an airtight container to keep soft.
What’s happening?
At first, Gak is slimy but as you mix it, the substance becomes firmer. It is a unique substance,
with properties of both a solid and a liquid. These types of substances are called nonNewtonian fluids.
Gak is a polymer. Polymers are made by joining huge numbers of individual molecules
together. The name polymer comes from the Greek words ‘poly’ meaning many and ‘meros’
meaning unit or part. A polymer is many molecules (units) joined together.
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How can I make slime?
The sodium borate (Borax) is a “cross-linker”. Cross-linkers connect polymer chains together.
The more the chains are linked (i.e. the more you mix), the more solid they become. It is harder
for polymers to move and flow when they are linked.
Why does it matter?
The plastics that we use daily are also polymers – polymers that can be molded or shaped into
many things.
Investigate further!
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

Try adding more or less sodium borate (Borax) to the solution. Try bouncing and
stretching it again. What happens?
What effect does temperature have on the Gak? Put your Gak in the fridge or warm it up
with your hands. Does anything change?
Leave the Gak out in the open for a few days and see what happens.
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