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What to Look for When Working with Knit Fabrics

Image of a piece of gray knit fabric with black cats. The fabric is being stretched by two hands. The fabric is on an ironing board covered with a beige fabric with sewing motifs in brown.
Rayon Jersey Fabric, Light and Stretchy

Selecting the right type of fabric for a sewing project is one of the strongest predictors of success. Many of my sewing failures happened because I did not follow the fabric suggestions for the patterns I was working with. The list of suggestions at the back of a pattern envelope is there to make sure that you have options but stick to the main requirements for that sewing project.

When it comes to knit fabrics, there are four elements you must consider when selecting your fabric: Stretch, Recovery, Stability, and Weight. These elements work together to give you the very best option for the garment you are about to create.

Woven vs Knit

Woven fabrics are created through the weaving of two sets of yarns. The yarns cross at right angles, creating the grain. Knit fabrics are created out of one single yarn looped continuously to produce a braided look. Wovens have no stretch while knits come in a continuum of stretchiness. Woven fabrics hold wrinkles while knits don’t.

What to Consider When Selecting Knits

When it comes to knit fabrics, there are four elements you must consider when selecting your fabric: Stretch, Recovery, Stability, and Weight. These elements work together to give you the very best option for the garment you are about to create.

Stretch

The amount of stretch in a knit fabric can tell you a lot about how the fabric will behave when you sew it. The stretchier the fabric, the more difficult it will be to work with it. If you want to know the stretch percent of a knit fabric you are working with, cut a 5” piece of the fabric and lay it next to a ruler. Hold the left side of the fabric at the zero mark of the ruler and the 5” at the 5-inch mark. Then, stretch the fabric, but make sure to do so without distorting the swatch. Write down that number.

Image of  ruler against a white background. There is a black rectangle representing a 5-inch piece of knit fabric. A pink arrow shows the direction of the stretch. There are five rectangles, from very light gray to dark gray, representing he amount of stretch percentage with every inch the fabric stretches.
The Stretch Test

Now, for some Math! Divide the stretched amount by 5 (the original length of the fabric), and you will get the percentage of stretch.

Example: 1 (amount of fabric stretched) / 5 (the original length of the fabric) = 0.2 or 20%

Recovery

This refers to how well a fabric rebounds to its original shape after being stretched. If you don’t want your clothing sagging as the day goes by, you need to pay close attention to this one. You want all of your knits to have good recovery—return to their original dimensions or very, VERY close to them. This is especially important when you are sewing very fitting garments. Spandex/elastane/Lycra is added to knit fabrics so that they have good recovery. 

You can test the recovery of a knit fabric using the same test we did for stretch. If the stretched fabric snaps back into shape once you let it go, you know this fabric recovers its previous shape well. If it sags, you know it doesn’t.

Stability

Stable fabric is one that does not get distorted when you are handling it, and it does not slip all over the place while you are sewing it. The stretchier a knit fabric is, the less stable it will be. The Internet seems to agree that stable knits have no more than 25% stretch—think of ponte, double knits, and heavier sweater knits. If you are a knit newbie, you might want to start with a more stable fabric, but make sure to check the pattern suggestions before selecting your fabric. 

Weight

Just like their woven counterparts, knit fabrics come in a variety of weights. Usually, weight and stability go together (the lighter, the less stable; the heavier, the more stable). When you are at the fabric store, it is easy to tell the weight of a fabric by feel (how I love to touch every single fabric at the fabric store! Is this socially acceptable? Can we do this now in these post-Covid days?) When you buy online, you have to rely on descriptions and the fabric weight chart. But what does it mean?

Fabric weight is calculated as grams per square meter (g/m2 or gsm) or in ounces per square yard (oz/yd2). Many online stores provide a chart with the weight of the fabric. The following chart will help you identify knit fabrics according to their weight and suggested uses.

Image of a chart for knit fabric classification by weight.
Knit Fabrics by Weight

Read the Envelope

The best way to avoid issues and fabric failures is to stick to the suggestions on the pattern envelope. They will guarantee the best possible result. Does this mean that you can never, ever start from the envelope? Nope. Once you get the hang of knit fabrics, you can try to experiment and use other fabrics not on the suggested list.

Image of a pattern envelope for a tight knit dress with long sleeves and a leg slit. The fabric suggestions blurb has been blown up to show the suggested fabrics.
Read the Envelope!

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