Diagonal Seamed Quilt Back – The John Flynn Method

on Mar 13, 2009 in Quilting | 23 comments

I’ve been making some quilt backs for Jacquie’s (Tall Grass Prairie Studio) Project Improv.

It provided the opportunity to try out a quilt back piecing method I’ve had bookmarked for a long time: The John Flynn Method of a Diagonal Seamed Back (page down to the bottom of that page where he has step-by-step photos and a printable set of instructions).

This method is intended to make optimal use of your fabric thereby minimizing the yardage needed. The backing fabric is cut on the diagonal, the two pieces are adjusted (basically you slide one side down) and then sewn back together. My first experiment came up short on that claim. One of two things most likely happened:

  1. I didn’t do it correctly (high probability this was the problem!).
  2. The results may vary depending on what size quilt back you’re attempting to create.

My target quilt back size was 56″ x 68″. I plugged this into John’s formula and came up with: LF = 68 + (( 68 x (57-42)) divided by (2 x 42) – 57). Don’t let the equation scare you! It’s very easy to plug the numbers in. The result of that is 106″ or 2 yards and 34″ of fabric. I rounded up and used a 3 yard cut.


1. Step 1, 2. Step 2 – Top View, 3. Step 2 – Side View, 4. Step 3, 5. Step 4 – Overview, 6. Step 4 – Close Up, 7. Step 5 – Double Checking It’s Wide Enough!, 8. Step 5, 9. Step 7 – Diagonal Seam Just to the Right of the Black Line

I debated on how to discuss this technique in a blog post. I’ll tell you, it’s very confusing the first time you do it. The best way to understand it is to go through the process yourself. I’m linking to the pictures I took as a resource if you do give it a try.

In a nutshell:

  • Fold the entire 3 yard length of fabric on the diagonal
  • Fold it on top of itself several times
  • Cut the folded edges off (this is very similar to creating bias strips from a folded piece of cloth)
  • Carefully pin the diagonal edges back together (offset enough to create the width you need)
  • Sew the diagonal seam

Final Results: my quilt back was short an inch on the length. I rounded up at every opportunity during the calculation. Again, user error is most likely the culprit which leads me to my ultimate opinion on this method of piecing a back: it’s awfully darn fussy for the results I got and the amount of time it took to cut the fabric!

Besides trusting you did all the math correctly, it’s very nerve wracking to cut your fabric in half along a diagonal line of 4 layers of folds. The bias edge then becomes a delicate beast needing to be stroked and coddled until the seam is finally sewn.

An additional limitation is that this method is only appropriate for a non-directional fabric design because of the way the patterns are angled and sewn back together.

I think this would be a good tool to know in the event you have a fabric backing that you really want to use but there’s not enough fabric to make it work with traditional piecing. It would be worthwhile to run the math and see if a diagonal seam might just get you the backing size you want.

I pieced the remaining backs using two additional methods. I’ll explain those next week (and guess what, one of them used LESS than 3 yards of fabric!)

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