Pour 4 cups of water in a saucepan and heat to boiling on high heat. Remove the pan from the heat as the water begins to boil.
Mix 1/4 cup of cornstarch with 1/2 cup of cold water in a mixing bowl with a spoon while the water is heating. Dissolve as much cornstarch in the cold water as possible.
Pour the boiling water into the mixing bowl, using caution not to splash, and mix the solution until the cornstarch is completely dissolved. Allow the cornstarch solution to cool completely to room temperature.
Funnel the cool cornstarch mixture into a plastic spray bottle. Shake the mixture vigorously just before using the solution. Lightly spray the fabric to make it only slightly damp, not wet or dripping. Iron the clothing as you normally would.