Parental supervision is recommended.
Close the bag tightly, making sure that most of the air is out. Pour the salt in a thin layer on the newspaper and let it dry. Repeat this for each color, giving each color its own piece of newspaper. When all colors are dry, pick the papers up one at a time and pour the salt back into ziploc bags or into separate compartments in an egg carton. Using your hands or the spoon, sprinkle each color, one at a time, into the jar, forming color layers.