January 02, 2007

Knits-Wovens - How to tame the stretch

Remember my previous blog on flower buttons? I promised to blog further on how this manufacturer worked with combining knits and wovens. Combining knits and wovens opens up wonderful design opportunities, that is until you try to sew the two together. The knits invariably stretch out of shape and the wovens will stubbornly refuse to stretch.

The most frustrating thing is trying to gather a skirt (with a high gather ratio) to a knit bodice. Imagine a pretty gathered taffeta skirt sewn to a stretch velvet top. While I am not going to explain every tip and trick out there, this well-loved jacket has some excellent examples of how to do this.

The most important thing to remember when combining the two is that knits will have to be stabilized in some way. This jacket has a facing which has been interfaced with a light-weight interfacing appropriate for a stretch fabric. In other words, after the interfacing is applied, the knit fabric retains some of its knit characteristics - it doesn't feel stiff as a board. The interfacing prevents the buttonholes from stretching out and the topstitching is straight and even.

As a design inspiration, you can see how the facing is an entirely different fabric. The neckline and center front seams would have been too bulky if faced with the french terry knit. Instead, they used a flower print jersey. I am sure this jacket was part of a two piece set that had a matching pair of flower print pants.

The gathered eyelet trim was pre-gathered onto a twill tape and then applied to the hem. The manufacturer could have applied a twill tape to the jacket and then gathered the trim directly to the hem. In either case, the knit fabric has to be stabilized to prevent stretching. The jacket, sleeve and pocket hems all have this gathered eyelet trim. Wow!

The manufacturer gets bonus points for their patch pocket application. The rounded pocket would have been very difficult to maintain the round shape and topstitch it without stretching. They used a 1/2" strip of interfacing around the edge of the pocket. This picture is a close-up of the inside of the pocket.

The final tip is not easily observable. In a factory, the sewing machines can be adjusted to help prevent stretching. How the fabric is fed through the machine is part of the reason store-bought knits look so good. This adjustment is often called the differential and it refers to the movement of the feed dogs. Industrial machines with differential feed have two sets of feed dogs. These feed dogs can be adjusted in how far they move back and forth and up and down, in relation to each other. The front feed dogs can either pull extra fabric or pull less in relation to the back feed. This is not to be confused with the stitch length, also controlled by the feed dogs. Few home machines, with the exception of some overlock sergers, have this ability, requiring knits to be stabilized even more when sewn. A walking-foot attachment, or machine, may help with seam distortion too. American and Efird has some good suggestions on sewing knits.

1 comment:

  1. This is interesting. I have this issue with diaper sewing, if you are not very careful the edges will ruffle and it looks oh-so-very homemade. I have even seen commercially made diapers that do this. Yikes!

    P.S. I love those flower buttons and am now obsessed with finding some for a sweater I knitted for my almost-2-year-old.