Here is the starch recipe It was a common recipe before liquid starch could be bought. The proper way to starch is too time consuming now days but you dip the fabric in a starch solution, roll up and put in the fridge over night and sprinkle with water before ironing the next day. Wash on Monday, iron on Tuesday. That was the way it was every week when I was a little girl and when my mother was a little girl. Everything fabric in the household was starched and ironed back then.
Dissolve half a teaspoon of cornstarch in a few tablespoons of cold water Add boiling water to make one cup, stirring constantly. Then add cold water to make 2 cups of starch. Let cool. Keep in fridge if not used up.