If you have ever admired a decorative hem on a knit skirt or top, it's very likely it was sewn with woolly nylon thread. Woolly nylon is a strong but soft thread that's primarily used in serged rolled hems for knit clothing, like swimwear, lingerie and active wear. Since the thread is so soft, it's preferable to cotton or polyester thread that can cause itching. All you need is a serger -- or what some call an overlock machine -- and a of couple spools of woolly nylon to create a soft, stretchy and attractive garment.
Threading the Serger With Wooly Nylon
Before you start sewing you will have to thread the serger with woolly nylon. Thread only the top and lower loopers. There are two basic methods for threading your loopers with woolly nylon.
If the serger is already threaded, the tie-on threading method will work. Cut the existing thread near the cone and replace the cone with the woolly nylon thread cone. Tie the woolly nylon thread onto the existing thread. Lift up the presser foot and gently pull the thread. The woolly nylon thread will follow the old thread all the way through the machine.
If the machine isn't previously threaded, start from the top of the machine, threading the woolly nylon to the loopers. Once you get to the small eye of the looper, either use a looper threading tool to thread the eye or dab some Fray Check on the end of the thread to keep it from splitting and then thread it through with tweezers. Thread the right and left needle with regular serger thread and you are ready to go.
Setting the Tension on the Serger
The next step is to adjust the thread tension. Woolly nylon requires a lower loop tension, usually a 1 or 2. Take a scrap of fabric that is the same as the fabric of the final garment and run the scrap under the presser foot. Adjust the thread tension up or down until the seam looks smooth and even. Once the seam looks perfect, you are ready to sew the garment.
Serging with Wooly Nylon
Woolly nylon is best for rolled hems and flat seams. When serging a hem or seam, be sure to keep the fabric taut but not stretched out. The woolly nylon will stretch during sewing, but it springs back and puffs out so there are no bare spots. Woolly nylon will give the finished garment a smooth satiny finish you cannot get from regular serger thread.
Finishing the Seam or Hem
Once you reach the end of your hem or seam, serge at least four inches from the end of the seam. Cut the threads and remove the garment from the serger. On a hem, you need to make sure the thread tail disappears. Take a large-eyed needle, like an upholstery needle, and thread it with the thread tail. On the side of the garment that doesn't show, pull the needle under the serged hem. Pull the needle out and the thread tail will be safely tucked under the seam. To ensure it doesn't come undone, put a spot of Fray Check over the end of the tail.
Take Care of Your Wooly Nylon
Woolly nylon is a strong but sensitive thread. You must never iron it directly or it will melt. Always use a press cloth over the seam or hem before ironing. Woolly nylon can dry out, so it is best stored in an airtight container or a sealed plastic bag. Take care of your woolly nylon and it will look great for years to come.