Prism99

I agree with tearing fabric for certain applications. Tearing along the lengthwise grain works well for getting straight borders, for example. However, tearing along the crosswise grain (from selvedge to selvedge) is somewhat problematic for piecing. Tearing always damages fabric fibers along the torn edge. It is harder to tear fabric along the crosswise grain, and crosswise tearing results in damage to the fibers up to 2" from the torn edge. Most of this damage cannot be seen by naked eye, but shows up under a microscope. This type of damage weakens the fabric, but will not show up in a quilt until many years down the line.

It was many years ago that I read an article on this topic from a quilter who took the time to examine the torn edges of her fabric under a microscope. She was a quilter who expected her quilts to be handed down in the family, and she was so disturbed by what she saw under the microscope that she went through her entire fabric stashing cutting 2" off every torn edge.

Not everyone expects their quilts to become family heirlooms, but I think it's a good idea for quilters to be aware of the difference between cut and torn fabric in terms of longevity.

Edit: I should add that cutting pieces for quilts exactly on the grain is not as important as it might seem, especially if the fabric is unwashed (meaning manufacturer's sizing is still in it) or starched. The most important reason to stay on-grain as much as possible is so that piecing remains accurate. Pieces cut on the bias stretch more easily; however, the amount of stretching depends on how far away from straight-of-grain the cut is. Fabric cut just a little off-grain will not stretch nearly as much as pieces cut on the true bias (45 degrees from straight-of-grain). For pieced quilts -- especially when the pieces are small -- having edges slightly off-grain is not a major problem, especially if the fabric has sizing or starch for stabilization.