I have taken a break from quilting for a couple of months because I was travelling.  When I started up again things just weren’t working very well.  I couldn’t seem to get the thread tension adjusted so that my free motion quilting looked good.  I decided it was time to go back to basics, do some testing  and create a reference sampler.

I made the sampler from a half yard of  a high thread count fine cotton that I buy by the bolt.  I use this fabric for printing photos onto fabric and for painting.  So it was available.  The test results I got might be different with a regular thread count cotton — perhaps I will do another test.  I just bought a large amount of Moda muslin so if I do another test, I will use that.  But for now here is what I found:

Results vary widely depending upon the thread used, both top and bobbin.  The best tension was 4.0 (the default setting on my machine) for a combination of Madeira size 40 Rayon top thread and size 100 silk bobbin thread.  The best tension for a Mettler size 50 cotton top thread and Superior Masterpiece 50 cotton bobbin thread was 7.0.  I will keep my sampler piece around for reference in the future when starting a new quilting project.

Here is a photo of my sampler, which is about 16 by 20 inches in size.   I used 80/20 batting and quilted a grid with rectangles about 3 1/2 inches high by 5 inches wide.  The exact dimensions don’t matter.  For each thread tension, I stitched in an area about  2 1/2 inches  by 3 1/2 inches, making sure to stitch several straight lines and sharp corners and a number of varying sized loops.  I used a .05  micron Pigma pen, but any fine point permanent marker will do.  It is important to make lots of notes on the fabric so you can remember how you stitched each section.

Sampler made from 1/2 yard of fabric.

As you probably know, there isn’t much consistency in thread sizing.  Mettler makes a rather “fat” size 50 thread.  Superior Masterpiece is a thinner size 50 thread, as are size 50 threads from Aurifil.  Even finer are the Superior “So Fine” polyester threads.  Superior Bottom Line is a size 60 polyester thread, thinner yet and intended for the bobbin.  Size 100 silk is extremely thin and available from both YLI and Superior.   All of these, and many others, are high quality threads that can be used in your quilts.

Here is a closeup of the front side of the Mettler/Masterpiece test.  The top view looked fairly good and about the same for all four of the tension settings I used.

Mettler tension test. Top thread Mettler size 50 gray. Bottom thread Superior Masterpiece size 50 white

And here is the back of the 4.0 and 5.0 tension settings.  As you can see, the gray top thread has come to the back and looks pretty bad, especially for the 4.0 setting.

Back side of Mettler tension test sampler, for 4.0 and 5.0 thread tensions, showing the gray top thread coming through

The 6.0 and 7.0 settings look much better.  The 7.0 is the best.  You probably can’t tell that from these photos.  I will show a couple of closeups of another test later that show you a better view, more like what you will see when you look at your own stitching close up.

Mettler test back side for thread tensions 6.0 and 7.0.

And here is my test using Superior Bottom Line, a size 60 polyester thread, in both top and bobbin.  The best tension setting was 5.0.

Superior Bottom Line front of tension test sample

Here is the closeup of the back for the tension 4.0 result.  You can see the top thread coming through and the bobbin thread taking a shorter path around the curve, because the top tension is too loose.

Superior Bottom Line thread tension 4.0 from the back, showing tension is too low.

And the same effect happened on the front for the tension 7.0 result.  Here the top tension is too tight so it pulls the bobbin thread up, and now the top thread is taking the shorter path around the curve.

Front side of Superior Bottom Line thread tension 7.0 stitching, showing bobbin thread pull through because the top tension is too tight.

These tension problems are less obvious when the top and bobbin threads are the same color, and when the color matches your fabric.  And an occasional tension irregularity will happen in any quilt if the thread doesn’t feed quite smoothly, or you don’t move your quilt smoothly.  But the overall result will be much prettier if you get the initial tension setting right.  A sampler like mine, stitched out on your own machine using the needle, threads, fabric, and batting you use most often, will help you get the setting right on every quilt with a minimum of testing.