Have you every followed a quilt instruction that says to press your seams open for a half square triangle? If you were anything like me, you would pull out your steam iron, put it on the open seam, and run it up and down the length of the seam to make sure it was nice and flat. Then, when you went to put that block together with others, you would realize it was wonky – not square. How could this be? You cut everything straight and used a scant 1/4 inch seam, just like the directions said! How could this be happening?
Well, you didn’t press the seam right. I know, you are saying that you used a hot iron and made sure the open seam was flat. How is that wrong? If you ran the iron along the seam with or without steam, you were ironing, not pressing. Believe it or not, there is a big difference, especially in quilting where being square is desirable – unlike social situations when you were in high school.
Pressing means applying even heat or pressure in one place, releasing the pressure and then setting it on another spot. Hold on a minute, you are probably thinking that pressing involves an iron right? Not always. You can use a finger, a stick, an iron or anything else you deem appropriate. The point is to apply pressure to open the seam. Many quilters will finger or stick press before they use an iron to make sure the seam is already open before you use heat to “set” the seam.
Ironing means sliding the iron along the fabric to smooth it out. You may do this on a finished product or yardage, but not on an unfinished block. Why – what is the difference? When you slide the hot, steamy iron across the fabric, you increase the possibility of warping the block as you push the fibers with the iron. Sometimes quilters will do this to “cheat” when something is NOT square in order to coax the fabric in a certain direction. But to keep it square, ironing is a No-No. So resist the temptation to glide that iron across the fabric. Pretend you are at the gym doing pressing exercises – Press one, lift and move, press two, lift and move….It will give your arm a little arm workout.
If you want to do a little experiment to see if this is true. Make two identical half square triangles. To do this, take two 10 inch by 10 inch squares and lay them right sides together. I recommend 10 inches, because you will need to move the iron to get it all. Using a pen, draw a diagonal line on one of these from corner to corner – this will be your cutting line. Sew 1/4 inch seam on each side of the cutting line. Then, cut along this line. When you open each piece, you should have a half square triangle. Press one with your finger or an iron. Iron the other. Now measure them. Which is more square?
I hope this post helped you tackle your wonky demons. Knowing the difference between pressing and ironing certainly helped me conquer mine!