Peel off the labels from the crayons and place the crayons in a clean, empty soup can.
Fill a pan with a 2 inches of water. Simmer on a burner at a medium heat. Place the tin can in the center of pan. Wait for the crayons to melt and remove the can from the pan with pot holders.
Pour the melted crayon into an old bowl or paper cup. Stir in a tablespoon of petroleum jelly for every two melted crayons. Allow the mixture to cool for up to 15 minutes. Once cool, stir again.
Scoop out the mixture with a plastic spoon into a container. Cover and allow it to harden into putty so it is ready for eventual application.