|Primer: Sewing Knits
Many new sewers are afraid of knits -- they
shouldn't be -- you don't need to be an expert to turn out beautiful knit
One of the great things about sewing knits is the
leeway they give you when fitting. A garment made from a stretchy fabric
doesn't have to fit as perfectly as one made from a woven, so knits
eliminate the pressure of exact measuring and altering of patterns. And
they're so comfortable to wear!
When constructing knit garments, one important rule
to remember is that if the fabric stretches, the seams must stretch
so the stitching doesn't pop as you bend and move in the garment. Whatever
type of machine you have, you can achieve flat, stretchy seams.
Whether made of cotton/polyester, cotton, wool, or
synthetics, each knit falls into one of several construction
categories: single knits; double knits.
- Single-knits like jersey, velour,
terry, and fleece look different on the reverse side, have cut edges that
curl, and usually have about 25-percent stretch.
- Double knits like interlock tend to be
more stable than single knits, often look the same on both sides, have cut
edges that don't curl, and stretch from 25 to 75 percent, depending on the
fiber and construction.
- Rib knits, constructed from alternating
knit and purl stitches in various combinations, may look the same or
different on opposite sides, tend not to curl, and have up to 100-percent
It's important to always pre-treat a fabric
before you sew it. The general rule is to wash the fabric using the
method you plan to use on the finished garment. This means that
cotton, linen, and synthetic knits should be washed and dried (in the dryer
if you plan to dry them this way later), and wool knits should be steamed
Smart pattern choices
When planning a knit garment, select a
pattern specifically designed for knits, rather than for woven fabrics,
because the pattern will have the correct amount of ease built into it. The
amount of stretch in the fabric will determine the style and size pattern
you choose. Check the pattern envelope for suggested fabrics and the amount
of stretch required for the style. If you choose a fabric with less stretch,
you'll need to add more ease.
Since knit fabric has built-in ease, you don't need
as much ease in the pattern as you would for a woven fabric. For example, a
couple of inches of bust ease is plenty for a fairly fitted knit
style, compared with the 5 in. of bust ease needed for most woven garments.
And a double-knit skirt hangs nicely with 2 in. of ease, while a woven skirt
would require at 3 inches or more.
You can achieve excellent results on
knits whether you own a basic sewing machine or a high end serger. A good
starting point is to use a long straight stitch of 9 stitches/in.,
stretching the seam as you sew it (as much as the fabric stretches easily)
to add elasticity. When the seam returns to its normal length, the stitches
are closer together and the upper and lower thread tensions have loosened.
Zigzag or stretch stitches to construct seams aren't necessary, and in the
writers opinion not as good..
For double knits that will stay pressed open, use a
5/8-in.-wide seam allowance. For single knits that tend to curl, use a
1/4-in.-wide seam, which you can finish two ways: either press it to one
side and topstitch for a professional look, or sew a second line of
stitching 1/8 in. from the first and then press to one side. The double-sewn
seam adds strength and helps keep the seam flat.
If you have a serger, you'll find serging a quick
way to assemble knits with a finished, factory look, and the seams will have
built-in elasticity, so you don't need to stretch them as you sew. Make sure
your stitch is balanced, adjusting the thread tension so that the stitch
doesn't bind or ruffle the seam. If your serger has differential feed, raise
the setting if your test seam looks wavy. For hemming soft knits, serge the
edge, turning up a 1/4-in. hem, then topstitching twice to get a stable,
Most knits don't ravel, unlike some woven fabrics
-- especially loosely woven ones, which can ravel until the seam allowance
has vanished. So serging or otherwise finishing seam allowances isn't
necessary with knits. Nonetheless, test whether your fabric ravels on a
swatch--some silky knits ravel on horizontal cuts, but most cottons and wool
You can sew an attractive hem on many knits with
double-needle topstitching, the finish that's used most often in
ready-to-wear. Use a 4-mm-wide double needle and 9 sts/in. for a
stretchy, professional-looking hem. If you're sewing a soft knit without
much body, topstitching the hem, especially with a twin needle, may result
in tunneling and rippled edges, since knits stretch more on the crossgrain.
You can stabilize the hem with strips of fusible interfacing, which also
anchor the hem during stitching. Many sewers prefer two rows of topstitching
rather than twin-needle stitching.
It's easiest to stabilize the hems before assembling
the garment. Prepare the hems by pressing them into place. Cut 1/2-in.-wide
strips of soft, all-bias knit fusible interfacing . Sew or serge the right
side of a strip to the wrong side of the hem edge (adhesive side is up).
After constructing the garment, fold the hem up, fuse it in place, and
topstitch from the right side.