I don't dip starch but rather spray starch. I use liquid starch and mix it 50:50 with water and put it in a sprayer that I got at a beauty supply place that is more of a fine mist. I use a large tub (favorite is the laundry basket with no holes from IKEA) to contain the over spray. Once sprayed I roll the fabric and put it in a plastic bag to mellow just like was done back in the day when you sprinkled clothes. Once the starch has had a chance to absorb into the fibers I iron it with a dry iron. By allowing it to absorb into the fibers you don't get flakes or residue on your iron.
Putting dipped fabric to dry on the shower wall is genius.