The 50/50 mix (using Sta-Flo) is what I use, but I do not dip the fabric. I "paint" the starch onto the yardage using a large wall painting brush, then wait a few minutes to make sure the starch has had a chance to penetrate the fibers of the fabric. It depends on how much yardage I am starching, but usually I just mix up 1 cup of water with 1 cup of starch at a time in a fairly small kitchen bowl (large enough for the paint brush to fit in, though). When I use that up, I mix up another batch.
I do this with dry, unwashed fabric but I think it would work fine with washed, damp fabric too.
Not sure how you dried the fabric. I just toss mine in the dryer, then iron with steam. Steam reactivates the starch.
I think you will find that the painting method uses a lot less starch than dipping.