Types of stitches
Self Welt-is a piping that is used in place of a regular seam to give pillows or cushions a complete, finished look.
Double Welt-Double-welted seams are used for cushions with boxed or welted style edges. Like the single corded cushions, where a thin strip of fabric if sewn around a heavy gauge string or cord and sewn into the seam of the cushions. With double welting, or "boxed double welting" as it is also commonly referred to, the welting is send into both the top and bottom seams of the sidewall fabric panel of the cushions along with the top and bottom fabric panels. The thickness of the cushions typically dictates how far apart the welting on the sidewalls will be.
Baseball Stitch- a stitch for making two edges just meet, worked under and over from the inside out.
French Seam- a strong, narrow seam in which the edges are not visible; usually used for fine fabrics, this seam is sewn twice, first on the right side and then turned in and stitched on the wrong side so that the raw ends of the fabric are enclosed in the seam, leaving a clean, polished, professional look.
Types of cushions
Boxed Edge-the construction of these cushions has a vertical sidewall that is the same height as the thickness of the cushion. These cushions are made by assembling the top and bottom section of the cut fabric to the sidewall fabric to form a box. This style of cushion is also commonly referred to as "welting". A five inch thick cushion would have a five inch thick sidewall sewn together with the top and bottom sections of the cushion fabric.
Knife Edge-are cushions that are made by sewing together the top and bottom fabric panels to make a more traditional sewing seam. These type cushions do not have a sidewall like the boxed edged or welted cushions. This style of cushions is most common for smaller thicknesses like one or two inch. Some even prefer using knife edge cushions for as much as three inches, however the finished look on thicker cushions with knife edges style begins to take on the appearance of a pointed or arrow head tip on the side of thicker cushions made with knife edge styling.
Waterfall-the fabric wraps over the sides from the top and bottom and forms small pleats around the curved front of the boxing strip.