Many of the designers we work with already know this, but the average person might not know the difference between a plain seam, a single top stitch or a double top stitch. Oftentimes, this is one of the first questions we ask when we are reupholstering a piece, or making a custom piece.
The type of stitch will depend on many things, but most importantly is the style of the piece, personal preference and the type of fabric used.
The plain seam, shown at the top, is very common, and often used with thick, nubby or high pile velvet or mohair. It's simple and clean.
A single welt, shown at the bottom, is a thin piece of fabric, cut on the bias, and wrapped around a cotton cord. It is then sewn into the seam and provides a decorative element to a piece of furniture or cushion. This can also be a contrast fabric, or pre made element/cord. The single welt shown is small, but welts can vary in size. One thing to keep in mind is that depending on the size of the welt, and position (on the edge of a seat cushion, for example), it can impact the comfort when you are sitting.
The single top stitch has the appearance of a welt, but lays flat. This is very often used on seat and back cushions and gives an otherwise plain fabric some dimension. On thick velvets and mohair, however, this can look a little sloppy sometimes because the fabric 'hairs' can end up sewn in different directions.
The double top stitch is also very popular; it starts as a plain seam and then a top stitch is run down each side of the seam using a double needle machine. The double top stitch originated in Italy in the 1970's, and a single needle machine was initially used. The top stitch back then was rarely straight, and the needle impressions were not even. Thank goodness for technology, because it's really beautiful, but it can get lost if you are using a nubby or boucle type of fabric.
What's your favorite stitch?