Doubleknit is a medium weight knit. The fabric is knit with two sets of interlocking thread, giving the finished product a more stable hand than lighter weight knits. The fiber contents vary, but common fibers include rayon, wool, cotton, and synthetics. Cotton and wool doubleknits have the texture and feel of a comfortable sweater. Rayon doubleknits can be produced to have the feel of buttery-soft cashmere. Synthetic doubleknits can be produced to mimic any natural-fiber knits, but with easier care properties. In some cases, the wrong side of the knit has a heathery appearance due to the use of a lighter color thread; the right side color is visible through this lighter thread. Doubleknits are a pleasure to sew. Try one, and you'll be hooked!
Your pretreatment will depend greatly on the fiber content. Cotton and wool knits of all kinds will shrink if washed in hot water. Pretreat these fabrics with handwashing, or wash in the delicate cycle of your washing machine with cold water. Lay flat to dry. Some synthetic doubleknits will machine wash beautifully; test a sample of your fabric with cold water machine washing. Lay flat to dry.
Use a 75/11 stretch needle, and polyester or cotton/poly thread.
On a conventional machine, a stretch stitch or small zigzag (2.5 length, 2.0 width) are good choices to maintain the stretch of the fabric. Hem with a stretch twin needle (2.5/75). On a serger, use a 3, 4, or 5 thread balanced stitch. If you own a coverstitch machine, this is a great fabric with which to use it!
Depending on the garment you choose to make, there may be a few areas that need the reinforcement of interfacing. For this fabric, a knit interfacing is necessary; you want the knit to maintain its stretch. Choose the lightest weight possible, such as So-Sheer for most applications. If you need a bit more strength, choose Fusi-Knit. Cut the interfacing in the same grain direction as the pattern piece, with the stretch of the interfacing matching the stretch of the fabric. Try to use a dark interfacing for the darker colored knits.
Cardigans, tanks, tees, simple skirts, hoodies, unstructured pants and jackets, pull-on hats and scarves are all great uses for doubleknits. Some pants patterns will work well for doubleknits; choose a pattern that has a classic fit to prevent strain.
Use the ‘wrong' side of a two-sided knit as a design feature. Stitch the seam allowances of your garment wrong sides together, press the seam open from the outside, and fold the seam allowances under on each side. Topstitch, coverstitch or zigzag in place. Or cut the flap of a pocket with the ‘wrong' side facing front. Wool doubleknits felt beautifully. Purchase more fabric than you need for your project if you plan to felt. Wash the fabric in hot water and dry in a hot dryer. I love the beefy hand that felting gives wool doubleknit!