Starch should help. If this were uncut fabric, I would suggest a different method but, since it is a quilt top already pieced, spray starch is what you should use. Spray the fabric, wait for the fabric fibers to absorb the starch (at least one minute but may take longer), then iron. You can allow the starch to dry if you are able to iron with steam; the steam will re-activate the starch. You may have to starch and iron several times to get it to stay smooth. If your humidity is extremely high, you may have to re-iron occasionally just because the humidity will soften the starch; however, as long as the starch remains in the fabric, ironing with steam will re-set it.
If you are planning on basting this quilt (as opposed to quilting with a longarm, in which case basting is not needed), I would recommend getting cotton or wool batting (not polyester) and using 505 spray to baste. This will help ensure that the top will stay flat until you are finished quilting, and will also help to make sure that the top adheres to the batting even though the top is starched.
Edit: The above assumes that your fabric has already been pieced and/or cut into pieces. If you are dealing with fabric before it is cut, I would recommend something different for the starching process.
Last edited by Prism99; 06-26-2014 at 04:34 PM.