IMHO, I think the problem is in the ironing/ pressing part of your work.
Not washing fabric before using and wetting it with the starch, if not evenly sprayed, causes the fabric to want swell up and to pull itself together in the wetter spots , The fibers are reacting to the amount of moisture. Less wet areas don't react as much as wetter areas. The result is uneven or wavy finish after pressing it.
Try washing a sample piece of fabric, then starch and press it. See if you get the same results.
When you starch leave it there for a minute to really soak into the fibers before you press. Take your time with it and try not to slide the iron over the fabric as suggested. Use an up and down action to press.
When I starch fabric, I do it twice. First on the back, and press, then flip to the front and do a lighter spray and press.
I have found this really helps to keep distortion at a minimum. I got this tip from Sharon Shambers web site.
peace
Last edited by ube quilting; 05-15-2015 at 01:07 PM.