The Basics of Stitch-and-Flip

If you have used my patterns in the past, you may be aware that I use the stitch-and-flip method often in my designs.  This technique, also know as snowballed corners or lost corners, makes it easy to add a triangle to the corner of a unit without having to cut either a triangle or a non-rectangular/non-square shape to which to sew the triangle.  It also avoid sewing along a cut bias edge.

How It Works

1.  Start with a base shape, either a square or rectangle, to which you want to add a corner, and a smaller square of the fabric you want in the corner.  The sides of the square should be 1/2" larger than the short sides of the triangles need to be in the finished quilt. 

You'll be sewing across the square diagonally from corner to corner, so you may like to draw a line to guide your sewing.  I like to use a mechanical pencil because it makes a fine line, which shows me more precisely where to stitch.  (I have included links to alternatives to marking at the end of this post.)

2.  With right sides together, tuck the square into the corner of the base shape, matching the edges in the corner.

3.  Sew along the diagonal.

4.  Fold the fabric back over the stitched line.  

5.  The folded corner should match the original perfectly.  (If it doesn't, rip the seam and try again.) 

6.  At this point I like to finger press the seam by running my fingernail along the seam.  This helps me make sure the fold is right up against the seam, and I'm less likely to distort the shape of either layer of fabric this way than if I use an iron.  After I finger press, I hit it with a hot iron to set the fold.

7.  After pressing, open up the fold and cut away excess fabric from the corer, cutting 1/4" away from the seam.  (Yes, I cut after I press.  I have found that keeping the full base shape while pressing helps stabilize the shape and I'm less likely to distort the unit.)

8.  Now fold the corner back to fill the unit's corner and you're done.

Additional Tips and Thoughts 

1. When the square is the same width as the base shape

You can also stitch-and-flip a corner when the square is the same width as the base shape.  In this case I recommend starting to sew from the side (see white arrow below) rather than the corner.  Starting from the corner sometimes leads to the corner getting caught in the machine.

2. Pay attention to the corner orientation

No amount of rotating a unit with a corner at the top right will turn the unit into one with a corner at the top left.

3. Trim as you go

When adding a second corner and the seam intersects the first corner, make sure you have trimmed away the excess fabric under the first corner before you add the second corner.  That new seam will prevent you from pulling the first corner back all the way to trim away the layers beneath.

Oops!

4. Why you should sew accurately rather than count on trimming

You may be tempted to sew a little off the diagonal so that when you fold back the corner it extends a little past the corner of the base shape, then trim everything even with the base shape.

This is fine if the the points of the triangle in the corner do not need to meet a particular part of whatever unit will be beside it.

If the points are meant to line up with some other element, you need to be accurate.  Consider the example below (this is a random example, not from any particular pattern).

I've shown the seam allowance in green below.  The point in the finished unit will be where the seam intersects the triangle.  

Here's what the two units together will look like, with the seam allowance taken up in the seam.  You see that the point meets the seam in the unit on the right.

Here's the same unit, but with the corner just a little larger, from using a larger square as "fudge room".

You can see below that once the seam allowance is taken up in the seam, that larger triangles results in a point that is lower than the seam it needs to meet in the other unit.

Similarly, a corner that is trimmed  too small because the seam was too far over towards the corner results in a point that is slightly above where it should be to meet the seam in the other unit.

5. Ways to sew on the diagonal without marking

I personally get better results sewing along a marked diagonal line on my squares, but there are other options.  I encourage you to try different methods if you wish and use the method that gives you the best results.

In particular, you might consider the Clearly Perfect Angles seam guide or Diagonal Seam Tape.  I don't endorse either of these products, but I've included the links so you can explore options.  You might also use the edge of a piece of masking tape in the same way you would use the Diagonal Seam Tape.

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I've discussed everything I could think of regarding stitch-and-flip corners.  If there's anything else you'd like me to address, leave a comment or email me.  I'll see what I can do.

Until next time, happy quilting!

Joanne