What To Do
To make slime you will need 125ml of PVA glue, 1/2 a teaspoon of bicarbonate of soda (baking soda), food colouring and 3/4 of a tablespoon of contact lens solution (the sort that has boric acid in the ingredients).
Pour all the PVA glue into a bowl and add the bicarbonate of soda. Mix them together well and then add a few drops of food colouring. Mix it in well until you get the slime colour you want. Add in the contact lens solution and begin to mix. You will need to mix it for a least 30 seconds before the slime starts to get ‘slimey’. Keep mixing until the mixture starts to come away from the bowl and then get your hands in and start kneading the mixture. Keep going and before long you will have a gooey-yucky slime. If you find that the mixture stays more like a liquid then add a little more contact lens solution.
The molecules in PVA glue do not hold together well this is why the glue seems like a liquid. The boric acid in the contact lens solution causes the molecules to join together into strings making it all slimey.