It is not really necessary...I have just found that a light starch or sizing keeps the fabric true and helps prevent stretching where I don't want it. If you don't want even a light starch all you have to do is say so and it won't happen...it just seems to help me keep fabric from streching. It is by no means stiff as I don't get the fabric soaked or even wet...just insures the piece lays flat and does not stretch.