T-Shirt Series: Purchasing Knit Fabrics

Not all knit fabrics are created equal. 

Once you've sewn with knits a couple of times you'll figure that out.  They stretch different, drape different, and bounce back different after being stretched some.  At times is it hard to distinguish what type of fabric they are talking about when manufacturers use certain names.  Here are a few brief definitions.

Double Knits--usually polyester knit, double knit basically means that the fabric looks exactly the same on both sides.  Ribbing is a good example of a double knit.  These are NOT good for structured garments.  You would use this for cuffs, waistbands, and neckbands.

Fiber content of this particular ribbing (from Jo-Ann's) is 95% cotton and 5% spandex.  The more spandex in the fabric the more stretchy it will be.  Also with spandex in the fiber content it will help the knit "rebound" back better after being stretched. 

Jersey--these knits will curl to the right side of the fabric when stretched on the crossgrain.  Right side shows a knit stitch and wrong side shows a purl stitch.  Drapeable with a moderate stretch. 

 This shows wrong side on left and right side on right

Interlock--Sometimes it is considered a Jersey knit.  However interlock tends to be a cotton / poly blend most common in 60% to 40% ratio.  It may not stretch as much as Jersey nor does it curl at the edges like Jersey does.  Great for making tees.  May not drape as well as other fiber content combinations if you are looking for something to use as embellishments.

Knit Lycra--cotton / lycra blends are used primarily for activewear, i.e. leotards and exercise gear.  Nylon / lycra blends are used for swimsuits and biking shorts.

____________________________________

Here is a stretch knit guide when determining how much stretch a knit fabric has when purchasing for a specific garment.  This is extremely helpful, if you are like me, and purchase a good portion of your fabrics as remnants, with no labeling available.

Stable Knits--this means that the knit stretches less than 10%.  For example: 4" of fabric stretches 1/2" or less. Double knits are an example.

Moderate Stretch Knits--jerseys and interlocks stretch 20-25%.  4" of fabric will stretch 1" to 1 1/4".

Stretch Knits--these knits stretch 50% or 4" will stretch an additional 2".

Super Stretch Knits--includes ribbing and swimwear that stretches 50-100%.  4" can stretch up to 8".

2-Way Stretch--means that the fabric only stretches in either the length or the width.  From a center point on the fabric it only stretches 2 ways: i.e. left and right OR up and down.

4-Way Stretch--means that the fabric stretches in all directions from a center point: left and right AND up and down--4 ways.

You can determine how much stretch is needed for a garment by looking at the pattern envelope.  Usually there will be a gauge printed on the envelope back showing that 4" of fabric needs to stretch to this point.

Here are a few more things to think about when talking about knit fabrics.

1. Pre-wash everything.  Knits shrink more and in larger amounts than woven fabrics.  And if you are like me and you buy end bolts or remnant pieces, the fabric contents aren't always listed on them.  Avoid the headache of garment shrinkage and pre-wash.  In fact some info I read said to wash/dry the fabric at least 3 TIMES before cutting.  This would explain why sometimes my shirts still feel like they've shrunk after prewashing and I've worn them a time or two.
2. Sometimes the excess finish on knits may cause skipped stitches when sewing.  (Just learned that myself--I may be doing more prewashing of swimwear fabric.)
3. Knits do not ravel like woven fabrics, but some may run and curl at the edges. 
4. Since knits do not ravel the seam and hem finishes may be optional. (Save yourself a step and don't worry if you don't own a serger.)

Some info found in "Sew Any Fabric" by Claire Schaeffer and "More Fabric Savvy" by Sanda Betzina.