This is a decorative stitch using two rows of blanket stitch. These two rows are made as mirror images and later whipped together.

You need to know the blanket stitch to continue with this tutorial.

barb_stitch_1     barb_stitch_2
Fig 1: Make a row of blanket stitch. Turn the fabric around and make another row of blanket stitch just adjacent to the previous row, as shown. The two rows should look like reflections of each other.   Fig 2: Now, come out with a contrasting colored thread and whip around the stitches of both the rows, as illustrated.
barb_stitch_3   Fig 3: A finished portion of the row looks like this.