Mix 3 gallons of water and 2 cups of liquid starch in a laundry sink. Immerse the shirt in the mixture.
Remove the saturated shirt from the sink, squeeze out water, and line dry the shirt. Take caution not to dry the shirt completely.
Lay the partially dried shirt on the ironing board. Iron the shirt, starting with both sides of the collar. Iron the sleeves, then the shirt body. Take caution not to wrinkle the already ironed parts.