Knit-ty Gritty
Seaming
Use a new ball-point, universal or stretch needle. A worn needle can cause skipped stitches. If you get skipped stitches with a universal needle, change to a ball-point needle for heavier fabrics or a stretch needle for finer knits. Use a size 60/8 or 75/11 needle for light- to mediumweight knits and size 80/12 or 90/14 for heavier knits.
Always make a test seam. If there are tiny holes along the seamline, the needle is too big or damaged and is breaking the fabric thread loops.
Set the machine at 8 to 10 stitches per inch (3 mm to 3.5 mm). Looser knits may require a longer stitch. If the stitches are too short, it restricts the fabric recovery and will result in rippling.
Incorporate stretch in the seams to add flexibility to the garment. Test the different methods below to see which works best for your fabric.
When straight-stitch seaming, gently stretch the fabric in front of and behind the presser foot as you sew.
Built-in stretch stitches automatically add stretch to the seam--don't stretch the fabric as it's sewn. Be certain the garment is already fitted; stretch stitches are extremely difficult to rip out without damaging the fabric.
Three- and four-thread serger stitches are also good for sewing knits. For even more stretch, use textured-nylon or -polyester thread (e.g.,Woolly Nylon) in the needle and loopers.
A narrow, short zigzag (1 mm length and 1 mm width) is a strong, yet flexible, stitch for T-shirt knits and wool jerseys. Make a test seam and spread it apart--if it "ladders," narrow and shorten the stitch. Don't stretch the seam while sewing.
Don't sew over pins. Hitting one can damage needles, the serger blade and possibly your machine. A blunt needle can cause snags, holes or runs in seams and topstitching.
To control curling fabric edges, use wash-away basting tape or a glue stick within the seam allowances when placing the pieces together. Allow the glue to dry completely before stitching to prevent gumming up the needle. Either of these aids can help align plaids, stripes or prints at the seams.
Some knit patterns have 1/4" seam allowances, others allow 5/8"--check the pattern instructions before seaming.
Use a double-stitched seam unless the knit has little stretch (like some double knits). Stitch on the seamline and again 1/8" to 1/4" from the first stitching in the seam allowance. When straight stitching both rows, stretch the seam equally both times. After stitching, carefully trim next to the second row of stitching, leaving a 1/4" seam allowance (4). Press the seam toward the garment back. A serger can do the seaming and trimming in one operation--be sure the needle stitches at the appropriate seamline location.
For knits that don't curl at the edges, stitch with a 5/8" seam and press the allowances open for flatter seams.
Knits don't ravel, so no seam finish is required. Adding a seam finish adds bulk; you want to reduce bulk whenever possible.
From the July 2004 issue of Sew News magazine.
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