Sizing has a higher scorching temperature than starch and I find that even if I need 2 coats it works better. Two light coats are better than 'saturating' the fabric. Also, I spray on one side, then flip it over and press on the other side.
I was taught in heirloom sewing that if you use sizing before you mark the fabric with a water soluable pen your marks don't 'penetrate' the fibers and is removed much more easily.
Peggy
Freezing in Fla where we're supposed to break 3 records in 24 hours. (Two record lows and one record minimum (high)!