If you are looking to add shirring to a garment, or want an easier way to get the appearance of smocking, here’s the trick.
Hand wind your bobbin with elastic thread (I’d recommend paying the extra few bucks for Gutterman thread, it’s more durable then most). Be sure not to pull or stretch your elastic as you wind.
Using the elastic thread for the bobbin and regular thread for the top, thread up your machine as usual. Lengthen your stitch length so it is slightly longer than usual (on our Janome’s I tend to use a stitch length of 3-3.5).
It’s not a bad idea to chalk in the sew lines on the good side of your garment before you begin. This will make it easier to have neat, evenly spaced shirring. I find that 1/2″ between each row looks best.
Now, sew your first line of shirring, backstitching a few stitches on either end. Line up your fabric for the next row. As you continue, be sure you are holding your fabric taught as it runs through the machine. Repeat this process for as many rows as is necessary.
Once you are done shirring, use your iron to steam your fabric. Hold your iron above your shirred fabric and press the steam button. This allows your fabric to settle into the gathers you have created.
Shirr Genius! (I just can’t help the bad puns)