Originally Posted by JulieR
Spray with water until damp, then fold and place in a plastic bag. Let sit for an hour so the moisture will distribute itself evenly; if you won't be able to get to it in an hour put the bag in the freezer and it'll keep.
Remove from the bag when you're ready and press with spray starch if desired.
The freezer method that JulieR mentioned works for cross stitch linen so I would think it would work for cotton. Dampen the fabric, place in a plastic bag, and place in the freezer. When you remove it from the freezer, iron.
If you try this, let us know if it works. :-)