Bonnet stitch is a variation of buttonhole that forms a line of stitches which have a upright twisted looped prongs. Jan Eaton in her Complete Stitch Encyclopedia states that she found this stitch in a 1923 issue of Embroidery Magazine.
Some stitches you look at the directions and they look distinctly uninspiring. Bonnet stitch is such a case. It looks like a double buttonhole or I call it a herringbone with its knickers in twist. However I urge you to try it out I think it will surprise you. You can use this stitch on even-weave or plain fabrics. It is quick and easy to work and will follow a curve well.
Bonnet stitch looks best in a thread with firm twist. So if you are one of those folks using up old stranded embroidery threads to test your stitches I can only encourage you to buy some perle thread. You are doing yourself a huge disservice if you never try other threads. Many of the surface stitches look nothing in stranded threads but work them in a thread with a firm twist and they come alive.
The sample is of Bonnet stitch worked in different threads. The first row is cotton Perle 8, the next rayon thread, followed by silk and the last row being a metallic.
Since Bonnet stitch is a member of the buttonhole family, it can be worked easily on a curve. If worked in freeform manner you can produce organic textured lines.
Also you can easily work this stitch in a circle.
How to work Bonnet Stitch
Work bonnet stitch from right to left between two imaginary lines. If you need to mark the line use a pen that will dissolve when moist or one of the quilters pen that disappear after a few days.
Bring the needle out on the bottom line. Make a small stitch on the top line with the needle pointing left.
Pull the needle through the fabric.
Slide the needle under the straight stitch you just made. You are not taking the needle through the fabric just slide it under the stitch with the needle pointing left. Pull the needle through.
On the bottom line insert the needle where you started to stitch. With the needle pointed left and the thread wrapped under the needle as illustrated, pull the needle through.
Take the needle to the top line and take a bite of the fabric as illustrated. This is the start of th enext stitch.
Continue along the line.
Bonnet stitch can be worked in rows or at different heights. Think of all the patterns you make with Buttonhole stitch as many of these you can adapt to Bonnet stitch too. It is a case of experimenting a little. It is also interesting if you work Bonnet stitch at different angles or use it to couch heavy threads to the fabric.
You can create patterns if you work this stitch row upon row or in this case in rows back to back.