I have been using Niagra and mix my own. Magic Sizing is my favorite. Does it come in a mix your own solution so you can get the stiffness, light, medium or stiff as a board quality?
Don't starch before I use
I measure the amount of fabric I will be using, cut it from the piece
Example: If i need 5 strips @ 2"wide, I will cut an 11 or 12" piece, enough for squaring, and just starch this amount.
I lay an extra tight weave fabric on my ironing board and can throw it in the wash, like an extra cover.
I Pump spray on the back of the material until it is wet, let the starch soak in for a minute so all the fibers are starched. I let it get almost dry, then press it. Then repeat. Yes, repeat.
My piecing has improved by leaps and bounds!
I do wish I could find Magic Sizing in a mix it yourself jug.
peace