Iceblossom

I press open and I have for decades. I have reasons for pressing open. I usually try to be gentle when discussing this, but the seam is every bit as strong whether it is pressed open or to the side, you are simply as wrong about your view as you believe your friend to be. While there are advantages and disadvantages to pressing open the seam strength is not one of them. I can show you my beginning quilts from 40-50 years ago to show you that the seams have been great all this time, those quilt fell apart due to lack of quilting holding down the solid pieces of fabric.

(edit: One of the reasons for pressing to the sides is due to low quality of fabric, not the seams. During a particular part of American history, the quality of fabric was rather low. Happens that period led up to what we think of quilts being today, 1900 or so. The people who learned to quilt in the 1930s learned from people who were dealing with unstable fabrics.

Most of today's fabrics are made differently, we buy "quilt shop quality". We, most of us, use machines. I believe folded seams are an artifact left from hand quilting and have no relevance to me using a machine and, of all things, irons. Big difference for me as a modern quilter and someone in a cabin with a hunk of metal that has to be heated on a wood stove.

My quilts are designed to be machine sewn, machine quilted, and machine washable.

Final thought -- if you took home ec when I did, you certainly learned to make all your clothing (pre-serger) with open seams. Trust me, through wear and laundering, they get a lot more stress than our quilt seams do and they hold up just fine.)

When we press open, we need a small stitch length. We need that same small stitch length if you do the modern techniques were you sew two pieces together first and then sub-cut the units. What I've noticed is basically all machines with a default stitch, that default stitch is way too long for quilting. On my Bernina, the stitch defaults to 2.5, I usually sew at 1.8 or less. To compound matters, when my machine starts it takes a couple little starting stitches smaller than the rest. For vintage machines, in terms of stitches to the inch, you should basically never be less than 12 stitches to an inch for seaming. Sure, denim or maybe some other things may come up.

For all quilting and whether you press to the side or not, a seam should not come apart easily, you should never lose entire stitches. To test, sew together two pieces of fabric. Tug gently at the start of the seam. No full stitches should ever come out. A slight loosening/a V is ok but not quite ideal.

I had a friend and she always had so many problems putting on her bindings, that was because she using something more like 8-10 stitches per inch. Yes, all her ending seams caused issues, they all came undone. But it wasn't because she was pressing open because she is presses to the side... She complained she couldn't see the stitches to take out mistakes if she made them smaller, I get that I don't see well either. But she was trading possible problems for guaranteed problems every time because of her "big stitch fix".