Working with Knits and Stretch Fabrics

First determine your stretch percentage.

Carefully mark with pins or chalk a 6 by 6 inch rectangle of your stretch fabric. Make sure it is clear which is the vertical (long) grain and which is the cross grain. Make sure the fabric's "memory" is good. It must return to the original size when you release the stretching. If the fabric stays stretched and does not return to its original shape, do not use the fabric!

Do not include the selvage which is more tightly woven or knit than the fabric.

Use a ruler or gridded mat, and measure an accurate 6 inch square of fabric.
Pull the cross grain, holding at 0 from the 6 inch end, as far as you can comfortably pull without breaking fingernails.

Measure and note the length to which you can safely pull the fabric.


Do the same for the vertical grain. You will want to enter the stretch of your fabric in options in the horizontal and vertical stretch boxes! The formula that follows will give you a precise stretch factor.

For most garments, you will only deal with the horizontal stretch. The vertical stretch should only be considered for garments that have an anchor for the long grain stretch, such as swimsuits.

If 6 inches stretches to 9 inches: 

9 - 6 = 3
3 divided by the original 6 = 50%; therefore, your stretch factor is 50%.

This is important. If you get a weird amount not listed on the table below,
such as 6 inches stretching to 8.325:


8.325 - 6 = 2.325

2.325 divided by 6 = 38.75 %. Use 39 %, i.e. round up or down to nearest %.


Table of stretch factors:

6 Stretching to 7 = 17%
6 Stretching to 7.25 = 21%
6 Stretching to 7.5 = 25%
6 Stretching to 8.5 = 42%
6 Stretching to 9 = 50%
6 stretching to 10 = 67%
6 stretching to 10.5 = 75%
6 stretching to 11= 83%
6 stretching to 12 = 100%
6 stretching to 13 = 116%
6 stretching to 14 = 133%

Stabilize your fabric if it is slippery and stretchy, by creating a tissue paper, fabric and tissue paper sandwich. Lay down a layer of white tissue wrapping paper, then your fabric in long lengths. Pat the fabric down with your fingertips to gently smooth the yardage. Allow it to sit a few hours before cutting so it is completely relaxed. Check and mark the grain carefully before covering with another layer of white tissue paper. Finally add the pattern pieces on top of the sandwich. Pin or weight in place. You are now ready to cut out your pattern pieces with scissors or a rotary cutter.

Warning! Fragile! Keep your pattern pieces with your fabric until you are ready to construct that piece. Store by laying the pattern pieces down carefully so you are not allowing the weight of the fabric to pull your curved sections out of shape.

Stitches:  

Your regular straight stitch is not appropriate for sewing with knits and stretch fabrics. Many sewing machines have a stretch stitch and a stretch "zigzag" stitch. See your machine manual for appropriate settings. A "zigzag" stitch may be used if you do not have the stretch stitch. You may need to adjust thread tension and stitch length and/or width.

Stay Tapes

Stretch fabrics require stabilization at neck, shoulder and armhole edges. Stay-stitching slightly within the seam allowance may be enough to stabilize neck and armholes. The use of *stay tapes, in the form of a seam tape or linen, cotton or synthetic seam binding,  Narrow Lights, or Seams Great, stitched to the seam allowance of the shoulder will help keep necklines from drooping and gaping.

* Stay tape is being used as a generic term and is any bias or woven tape which reinforces the seam so it will not grow. A commercial product called "Stay Tape" is sheer and lightweight and does not add bulk.

Thread:  

It is best to use the same type of high quality thread as the fiber content of your fabric. Use an organic thread such as cotton for organic fibers. Use a synthetic poly thread for synthetic and synthetic blend fabrics.

Needles:  

There are 2 types of stretch needles on the market. Ball point needles have a small rounded tip which will not perforate the fibers, but will separate them as you sew. Stretch needles are marked HS or stretch. Use the appropriate size and type of needle for your fabric. See your sewing machine manual for additional information.

Make a Stitch Sample:

Make a sample of the stitch setting and tension adjustments on a fabric scrap that is doubled over so you are sewing the sample at the same thickness your garment seam will be. Correct the settings as needed. See your sewing machine manual for more details.

When sewing stretch fabrics, position the fabric under your sewing machine needle, put the needle down first, and then lower the presser foot. Sew slowly for a few inches. If a bubble starts to form, *stop, put the needle down and lift the presser foot to release the bubble. Continue sewing for a few more inches, then repeat from *.

Stretch as you Sew: 

When sewing necklines and armholes, you may wish to stretch the fabric gently as you sew. Use both the left hand behind the needle, and the right hand in front of the needle. This will allow the stitch line to stretch and not pop out when you wear the garment. Too much stretching will deform the fabric. It is best to practice this on your sample.