We Have A Totally No-Fail Slime Recipe!

By: Rachel Brittliff, Curious Kid's Science

Slime is all the rage at the moment but it can be hard to find a recipe that works rather than just making goopy slop.

Never fear, this slime recipe won’t let you down.

What You'll Need

PVA (Craft) Glue: Woolworths, Spotlight, Bunnings. Not all white craft glue is PVA so make sure that you read the label. PVA stands for Poly(vinyl acetate) which is sometimes written in full on the bottle of glue.

Bicarbonate of soda: Most grocery stores. I have never tried baking powder but this contains bicarbonate of soda so if you have some on hand you could give that a go.

Buffered Saline: Pharmacy. Make sure that the saline that you get says “buffered” or check the bottle for the ingredient “borate”. Plain saline will not work.

Food Colouring: Grocery stores. The baking aisle of the grocery store will have lots of options. I have only ever used liquid food colours.

Here's What To Do: It's Easy!

1. Place some glue in a largish bowl that you don’t use for cooking purposes (I bought one at K-Mart for $2 that I keep just for science and craft). The amount of glue does not matter but about 100ml is probably a good starting point.

2. Add colour if you are adding colour. Start with a small amount and stir it through the glue then just keep adding until you are happy.

3. Put a teaspoon of bicarbonate of soda into about 5ml of water and stir until it is dissolved.

4. Add the water and bicarbonate of soda to the glue. Stir well.

5. Add about 5ml of saline to the glue mixture and stir.

At this point, the glue should start to become stringy and begin to come together. Keep stirring until you stop seeing any changes in the mixture. Gradually add more saline until the mixture has come together. Stop when it becomes a bit too stiff to stir easily.

When the mixture is a bit too difficult to stir, use your hands (or get the kids to use theirs) to work the mixture in the bowl. The slime will become firmer until it no longer sticks to the kids’ hands and can be stretched and moulded into a ball shape.

The more saline you add, the stiffer the mixture will get but too much saline will cause the mixture to break down. If that happens, add a little more bicarbonate of soda. 

The Science Behind The Slime

PVA glue contains polymers. To form the stretchy slime the polymers need to join together in chains. The borate ions in the saline create a chemical reaction with the PVA to link the polymers into chains.

For more awesome science experiments for little ones, visit Curious Kids' Science. 

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