Knit fabrics, known for their stretchability, can fray or develop holes if the threads are cut during sewing. Therefore, it's essential to choose the right needles and threads designed for knits.
1. Choosing the Right Needle for Your Fabric
Knit needles have rounded tips that allow them to sew without cutting the yarns of the fabric. These needles are suitable for both domestic sewing machines and overlock machines (sergers). There's a variety of needle sizes available, tailored to the thickness of your fabric:
- For lightweight fabrics (#9): Ideal for thin fabrics like leggings, undergarments, lace, or swimwear.
- For medium-weight fabrics (#11): Perfect for T-shirt material or sportswear knits.
- For heavy-weight fabrics (#14): Use this for thicker materials like fleece or sweatshirt fabric.
2. Selecting the Appropriate Thread for Your Fabric
To prevent threads from snapping when the knit fabric stretches, primarily use knit-specific threads (polyester threads). For knits that do not stretch much or when using an overlock machine, spun threads may be suitable.
When sewing with a domestic sewing machine
- Top thread: Polyester thread (No. 50)
- Bobbin thread: Woolly nylon thread (commonly available in one size) *Note: Computerized sewing machines automatically adjust the thread tension, so combining polyester and woolly nylon may not yield the best tension. We recommend testing this on your machine at home.
When sewing with an overlock machine
- Spun thread: Use No. 90 for lightweight fabrics, No. 60 for medium-weight fabrics, and No. 30 for heavy-weight fabrics. *Generally, four threads (or three) of spun thread are sufficient. However, for fitted garments made from highly stretchable fabrics, you might use polyester thread in the needles and woolly nylon in the loopers.
- If in doubt about color, opt for the darker shade.
- For overlock machines, instead of buying four (or three) new spools for each fabric thickness, starting with No. 90 thread is usually safe.
- We always recommend doing a test stitch to ensure compatibility between the thread combination and fabric.