For heavy starching (say, for backing fabric or for fabric that will be cut into bias strips), I mix a 1:1 solution of Sta-Flo liquid laundry starch, "paint" this solution on the fabric with a large wall painting brush (kitchen island works well for this), wait a couple of minutes to make sure the fibers have absorbed the starch, toss in dryer, then iron with steam. There is no way I can get fabric starched this heavily with spray starch. I do use spray starch on my pieced tops.