Sewing Lycra Blends
by Sandra Betzina
from Threads #86, pp. 46-49
If you've been to a fabric store lately or have been perusing your mail-order swatches, you're sure to have noticed the word Lycra creeping into more and more fabric labels, frequently in fabrics you'd least expect. That's because Lycra, a stretchy fiber most famous for putting the spring into nylon exercisewear, swimwear, and foundation garments, is turning up blended in tiny amounts with natural fibers, such as wool, linen, cotton, and silk, not to mention paired with rayon and polyester microfiber. Lycra's expansion into the fashion-fabric arena includes both knits and wovens, so these days you're just as likely to see a woven wool suiting blended with 1% Lycra fiber as you are a wool or silk jersey given more resilience by 3 to 5% Lycra.
|More on fabric:
• Guide to Fibers
• Know Your Knits
• Video: How to Identify Fabrics with a Burn Test
• 19 Essential Fabric Tips & Tricks You Should Know
|These samples include Lycra-blend silk, wool, linen, cotton, and man-made fibers, such as rayon and polyester microfiber, which all look like their single-fiber counterparts but shake off wrinkles when Lycra is added.|
These fabrics look just like their all-natural counterparts, so they're suitable for a wide range of garments, from career- and daywear to special-occasion dressing. But Lycra-blend fabrics have two significant differences from all-natural fibers: a degree of stretch not present in the natural fiber and a greater resistance to wrinkling. The advantage of sewing with Lycra-blended natural fibers is obvious: The tiny bit of synthetic added to a natural-fiber yarn means a wool-and-Lycra or linen-and-Lycra jacket can shake off creases and still offer the warm or cool comfort you'd expect from plain wool or linen. Woven Lycra blends have the additional advantage of allowing sewers to more closely fit a pattern than would be comfortable in a fabric without Lycra. Tailored or close-fitting pants sewn in Lycra blends have less tendency to bag out in the seat or knees. And sewing with the fabric is surprisingly easy, too. Just a few minor adjustments to the usual sewing process for all-natural fiber fabrics will have you sewing Lycra blends like a professional.
Preparing the fabric
The common sense rules that apply to preparing fabrics for cutting, whether knit or woven, still apply when Lycra is added to the mixture. Knits that can be machine-washed should be preshrunk in a warm-water machine wash on the gentle cycle, using a mild detergent, and then dried on low heat. Machine-washable Lycra wovens, such as linen, microfiber, and cotton blends, take a regular cycle for both washing and drying. When hand-washing is appropriate, as for some silks, use cool water and hang to dry, or if you prefer, have the fabric dry-cleaned. Garments made of wool and Lycra blends, both knit and woven, will need to be dry-cleaned, but yardage can be preshrunk by holding a steam iron 1/2 in. above the fabric's surface.
A few ground rules
Lycra-blend knits and wovens also share some special needs in terms of layout directions, cutting implements, thread, and zipper treatments. After the fabric is preshrunk, even out the crossgrain ends with a T-square, and lay out the pattern with the greatest amount of stretch going around the body, whether cross-grain or lengthwise.
Sharp tools are a must with this fabric because you don't want to stretch it as you cut. So use your best scissors or a rotary cutter, and sharp, fine pins to avoid snags.
You won't need special presser feet for sewing Lycra blends, but a good-quality, all-purpose polyester thread is your best bet because the thread itself has some stretch built in. When threading the bobbin, be sure not to wind it too fast, or the thread will be stretched and the seams puckered. Resist the urge to stretch seams as you sew; using a narrow zigzag (of the lengths specified below for knits or wovens) will add all the stretch your seams need.
An invisible zipper is most compatible with Lycra blends. Stabilizing the seam allowances with lightweight 1/2-in. fusible strips cut in the fusible's nonstretch direction will prevent zippers from bulging.
Handling Lycra-blend knits
Before laying out your pattern and cutting a Lycra knit, check the fabric for defects and snags, so you can work around them. Crease marks where the fabric was folded on the bolt can be permanent, so you may have to refold the yardage for pattern layout. Consider simplifying your pattern to make sewing with Lycra-blend knits easier. For example, eliminate neck and armhole facings by binding the raw edges with self-fabric cut in the direction of the fabric's greatest stretch (you can use the bias-binder attachment to apply this). It's also best to mark the pattern's notches using 1/8-in. snips into the seam allowance because fabric markers can leave stains.
For sewing nylon-Lycra knits, use a 70/10 SUK ballpoint needle; for all other Lycra-blend knits, a 75/11 HS stretch needle is appropriate. Areas of stress, like crotch and underarm seams, need a 2.5mm triple stitch ; other seams, such as those at side, inner leg, and casings, take a narrow, .05mm- to 1.5mm-long zigzag. Test seams after sewing by stretching as much as possible. If stitches break, loosen the top thread tension, and test again until there's no breakage.
For seam-edge finishes, serge together with a three- or four-thread overlock stitch, using woolly nylon in both loopers. Don't use a five-thread overlock stitch because it has no elasticity. Topstitching on Lycra knits is done with a ZWI HS stretch twin-needle, using woolly nylon hand-wrapped onto the bobbin and in the loopers. Using the stretch twin needle (identified by its blue band) is important, or skipped stitches will result. To flatten out the ridge that sometimes appears between rows of topstitching, loosen the top-thread tension.
Options for hems include the cover hem on the serger, which produces two stitch lines on top and a serged stitch on the underside, or a flat-lock stitch, which looks like a three-thread serged stitch on top and a ladder stitch on the back.
As with many knits, Lycra-blend knits rarely support buttonholes well, but if you dare to try, test first, being sure to cord the buttonholes to prevent their stretching out of shape from use.