pbf

To pbf is to work a purl stitch into the back loop of a stitch, then immediately work a purl stitch into the front loop of the same stitch, producing two stitches from one. The abbreviation stands for "purl back and front." This technique mirrors its knit-side counterpart (kbf) and serves as a foundational increase method in hand knitting and some machine processes.

The mechanic works because the single loop of yarn still seated on the needle allows the working yarn to wrap twice around it before the original stitch is cast off. When the needle passes through the back loop first, then the front, two distinct new stitches form along the same base. The order matters: back loop first ensures consistent stitch orientation and prevents twisted stitches in most stitch patterns.

Application and variants

Pbf appears most often in lace knitting, shaping garment edges, and decorative increases where the maker wants the increase itself to become a visible design element. It pairs logically with kbf on the knit side to create symmetrical increases in raglan sleeves or eyelet patterns. Some patterns call for the reverse order (front and back) to create a distinct visual effect. Machine knitting can execute pbf through programmed needle selection, though hand knitters perform it manually by looping the yarn twice into the same base stitch.

The stitch sits firmly in intermediate knitting: beginners usually learn simpler increase methods like yarn overs or lifted increases, while pbf requires confident needle control to avoid splitting the yarn or tangling working loops. Tension inconsistency at pbf stitches is common, creating visible bumps or loose stitches that disrupt even gauge. The base stitch itself remains engaged until both new stitches are secured, making timing and loop management the primary technical challenge.