Okay, now for some practical information. Thread tension is the bane of every quilter. It is important because it affects the long-term durability of your quilt, and is an important part of quilt show judging criteria (more on that in another post). If your tension is unbalanced, those stitch lines are not as secure as they should be. If the thread that is lying flat breaks, the stitches will loosen and fall out.
Getting and keeping good thread tension is your goal and some days will be better than others on that score. It helps to have a basic understanding of how thread tension works. The folks at Superior Threads have a TON of great information, including this diagram on the tug of war between top and bottom thread tension. (FYI, I do not get paid by Superior Threads, but I am a big fan. They carry a wide variety of very high quality thread.)
Note that BALANCED tension is what is important, and the only way to know if your tension is balanced is to look for top thread pulling to the bottom, or bobbin thread pulling to the top of your quilt. Run your finger along the stitch line. Does it feel smooth, or bumpy? If it is bumpy, or you hear your fingernail running along the stitch line, you need to adjust your tension.
Here’s a little sample quilt I use in my classes showing balanced and unbalanced thread tension:
Notice the ‘eye lashes’ on stitch line 2? Bad, bad, unbalanced tension!
Notice how stitch line 3 looks a lot like the balanced tension on stitch line 1? That’s because the bobbin thread tension is too high/tight and the top thread is pulling to the back of the quilt. You can’t see the problem while you are quilting, only when you stop to look at the back. This is the most diabolical of all tension problems.
So the lesson for today is, test for tension just like you vote… early and often.
What is your best test for stitch tension?