A Guide to Understanding Knit Fabrics

Blogger: Jenn Meitin Williams

A Guide to Understanding Knit Fabrics

Choosing what type of knit fabric to use can be one of the most daunting tasks when it comes to knit sewing projects. A knit fabric is a substrate that stretches. Stretch can vary greatly among different types of knit fabrics and that is one of the qualities that makes selecting a specific knit difficult. The best way to understand knit fabrics is to use it and sew with it! This blog post will provide some insight into the function and feel of various types of knit fabrics.

There are four different types of knit fabric that are frequently used: sweater knit, double brushed polyester, cotton spandex french terry, and rayon spandex french terry.

For reference, the model pictured is 5´8” with the following measurements: upper bust 35.5”, full bust 37.5”, waist 29”, hip 38.5”. All four sweaters are a size 8 bust graded to a size 6 hip with no length added at the arms or the bodice.

Before starting any project, it is important to determine is the amount of stretch and recovery that the fabric has.

Patterns typically call for a fabric with a certain percentage of horizontal and vertical stretch. Vertical stretch is not always necessary for all knit garments but vertical stretch is very important for items like leggings, leotards, and fitted shirts. The stretch can be easily determined by taking a 4-inch square swatch and stretching it over a ruler horizontally and vertically. If the 4-inch square swatch stretches to 6-inches horizontally, the fabric has 50% horizontal stretch.

Here’s a simple formula to help:

Once the fabric is stretched, if the swatch goes back to it’s original 4-inches, the fabric has really nice recovery. Knit fabric with good recovery is an excellent choice for neckbands, arm bands, cuffs, etc. If the fabric does not bounce back to 4-inches but instead recovers to 5- inches, the fabric does not have great recovery and would not be ideal for the neckbands, arm bands, cuffs, etc. If knit fabric with poor recovery is used for a neckband for instance, the neck opening will likely end up wider than intended and look stretched out and sloppy.

Let's test the four fabrics mentioned above.

Now that the stretch percentage has been determined, it is easier to understand how each fabric will fit for a certain pattern. The pattern used for this demonstration is the Sausalito Sweater. This sweater pattern recommends using a fabric with at least 30% horizontal stretch. Vertical stretch is not necessary.

First up is the sweater knit. This fabric is a heavier sweater knit. Because of the vertical stretch, it hangs very differently than the others. It gives a very slouchy, loose feel to the sweater. The weight of the fabric is being pulled on by gravity which makes it look and feel a little more oversized. Sweater knit also makes the neckline seem wider and the cuffs and hem band seem looser.

Next is the double brushed polyester. This fabric also has a really nice stretch and recovery. It is lighter weight than the sweater knit so gravity is not as much of a factor. This fabric also has a nice drape which causes it to follow the contour of the body a little more. The neckline is a touch more fitted and the cuffs and hem band are too.

The cotton spandex french terry is the most structured fabric of them all. It is a bit heavier and stiffer and does not drape like the others. This fabric provides a boxier look as the fabric tends to puff out instead of following the body. Because of the stiffer feel, the cuffs and neckband will seem tighter. While this fabric does have vertical stretch, it does not “hang” due to gravity. It stays put unless tugged on.

Lastly is the rayon spandex french terry. This fabric has no vertical stretch and has the least amount of horizontal stretch. It is the most fitted feeling of them all. Rayon spandex french terry does have decent drape, so it won’t appear to give a boxy look like the cotton spandex french terry. These cuffs and bands are the tightest feeling of them all.

In summary, it is always important to check what stretch the pattern calls for and determine what kind of fit is desired. When working with knits, it’s not one type fits all situations. Every knit has very different qualities and a knit that might work well for one style could be the wrong choice for something else!

Featured sweaters were sewn with the Styla Sausalito pattern.