I hate to tell you this but some papers actually shrink when you apply a hot iron to them :shock: this can distort your blocks , depends what paper your using, doesn't usually happen with the heavier printer paper, but I use Lunch wrap which comes on a roll, is lighter, easier to tear out and cheap :lol:
It took me ages to figure this out, I couldn't understand why my blocks weren't turning out the right size/shape. I did an experiment, cut out two 12" squares of the same paper and pressed one, lost 3/8" on the one I pressed. I press all my paper now b4 tracing my pattern, no more prob :D