I dipped all the characters into the slime and none of them changed color? Why?

The slime dip must be very cold to reveal the color change character. For best results, please place in freezer for at least 20 minutes prior to dipping your characters (Hint: Slime should be chilled to 32F/0C or colder). Alternatively, you can fill a bowl with ice water and dip your characters to reveal the one that changes color.