We bought some slime at a craft fair a while back and my kids loved playing with it. It kept them busy for a surprisingly long time. I thought that they might enjoy making some of their own and it turns out that playing with slime that you made yourself is even better than just playing with slime.
You will need: Borax, white glue, water, cups or bowls, spoon, glitter (optional), food coloring (optional)
- Stir together 1/4 cup of glue and 1/4 cup of water.
- Add glitter or food coloring to this water/glue mixture, if desired.
- In a separate cup, stir 1/8 tsp of Borax into 1/4 cup water.
- Pour the borax/water mixture into the glue/water mixture and start stirring. It will start to thicken pretty much right away.
- Keep stirring until it holds its shape a little bit and then scoop it out of the cup and knead for a few minutes until it forms a nice consistency.
- Store in a plastic bag or resealable container to use again later.
Here is what’s going on: You are seeing a the formation of a cross-linked polymer. Glue contains polyvinyl acetate, which is a type of chemical that is called a polymer. A polymer is a large molecule that is made up of lots of repeating subunits. You can think of it kind of like a chain with lots of individual links or necklace that is a long strand of individual beads. The formula for polyvinyl acetate is (C4H6O2)n. The C4H6O2 is the subunit and the “n” means that the polymer is made up of some number (n) of this subunit. When glue is by itself (or stirred into water) the polymer strands can move past each other without sticking or bonding to each other. Borax contains the chemical sodium borate (Na2[B4O5(OH)4]·8H2O) and adding this changes that. When we add sodium borate to the glue, it starts getting stuck to the strands of polymers. It can get stuck to more than one strand at a time, so it starts connecting the polymer pieces to each other. The more you mix the sodium borate and polyvinyl acetate together, the more of these bonds form and eventually the polymer pieces get all tangled up with each other. This is called cross-linking and it turns the liquidy glue into this stretchy slimy substance that is pretty fun to play with.