Fabric 101: Knits

Knit fabrics are my favorite. Well… they are kind of a pain to sew with, but they are extremely comfortable to wear, so I think it’s extremely useful to learn how to work with this type of fabric. 

For those of you just getting started learning about fabric, knits are a general category of fabric that involve looping and interlocking the yarns together rather than weaving them. It’s just like when someone knits a blanket at home, but on a much smaller scale (and done with machines). This sets it apart from woven fabrics—the other primary category of textile construction—which are created by weaving horizontal and vertical fibers together in an under-and-over pattern.

The most basic way to think of knit material is to say that they are fabrics that stretch. This is an oversimplification, but if you’re a beginner it’s a very useful way of differentiating knit from woven fabrics. Unlike woven fabrics that have a more static and rigid structure, knit fabrics can stretch and recover, making them more comfortable (and easier to get the right fit).

Sewing knits is somewhat challenging (nothing you can’t handle with a little practice). I’ll get into this more later on in the article with my tips for sewing knits. But if you just picked up a “knit’s only” pattern or you just really want to sew with knits, I hope this article will give you the basic information and confidence you need to get started.

What are knit fabrics?

In your everyday life, you encounter knit fabrics frequently. Your cozy sweaters, comfy yoga pants, everyday T-shirts, and high-stretch athletic wear are all made from knit fabrics. 

Unlike woven fabrics, where fibers run perpendicular to each other, knit fabrics involve a single yarn being looped repeatedly to create the structure of the fabric. This different type of fabric construction gives knits some unique characteristics that set them apart from woven fabrics.

The specific properties of knit fabrics, including their drape, warmth, and moisture-wicking capabilities, vary depending on the type of yarn used and the style of knitting employed. For example, a jersey fabric typically used for t-shirts is quite different from a rib knit, often used in cuffs and collars.

Key Differences between Knit and Woven Fabrics:

• Stretch: Knit fabrics are inherently more stretchable. While different types of knit fabrics will have different amounts of natural stretch, woven fabrics will not stretch unless they are made from synthetic, elastic fibers (spandex or elastane)
• Drape: While it can vary depending on the fabric, most knit materials will have a heavier, and more fluid drape than woven fabrics.
• Fraying: Unlike woven fabrics, knits do not fray. When you cut out the pattern pieces the raw edges should remain in-tact.
• Wrinkling: As a general rule, knit fabrics are more wrinkle resistant than woven fabrics. This does depend on fiber used in the fabric construction, but you can still expect to spend a lot less time ironing or steaming knit garments.
• Pilling and snagging: Knit fabric is more prone to pilling than woven fabric, while wovens are more likely to snag and rip.

Understanding stretch properties of knit fabrics

Some knit fabrics are extremely stretchy while others barely stretch at all. Some terms that are useful in understanding the stretch qualities of knit fabrics include:

• Stable knits: These fabrics have very little or no stretch. Instead, they are typically used for projects that require more structure, such as jackets and bottomweight garments. Fleece and French Terry often fall into the stable knit category.
• Moderate Stretch: Most knits would be considered moderate stretch. These fabrics will have somewhere around a 25% to 75% stretch in at least one direction and sometimes both. Most jersey, interlock, and ribbed knit will fall under this category.
• High Stretch: High stretch knit fabrics will incorporate elastic fibers (spandex/elastane) to enhance the stretching capabilities of the material. These are used for activewear, swimwear, bodysuits, and other types of garments that require extensive flexibility while also having a close fit.
• High recovery: This term means that the fabric will bounce back into shape quickly after it’s been stretched. So if you stretch out the material as far as it will go and then release it, a fabric with high recovery will immediately snap back to its original size
• Low recovery: The opposite of high recovery, if a material has low stretch recovery it will take some time before the fabric returns to its original shape. When you stretch and release the fabric, it will look stretched out and wonky until it’s had time to recover.
• 2-way stretch (one direction stretch): This means that the fabric will only stretch along the width of the fabric and little to no stretch along the length.
• 4-way stretch (two direction or all direction stretch): This means that the fabric will stretch both across the width of the fabric and along the length. Usually, it will still have slightly more stretch across the width, but will still have considerable stretch in both directions.

When you are using patterns made for knit fabrics, always look for the stretch guide. This is a little diagram that tells you how far the material needs to stretch for it to work with the pattern. Typically, the more structured and loose the clothing is, the less stretch will be required.

What are the different types of knit fabrics?

Knit fabrics is an overall category of fabrics. The way a material is knitted will dramatically affect the characteristics of the final fabric from lightweight and flowy, to warm and cozy. These are some of the common types of knit fabrics that you’ll come across:

• Jersey: This is a light to medium weight single-knit fabric with a smooth, flat face. This is probably the most common type of knit fabric you will come across. It offers moderate stretch and is well-suited for a wide range of garments, including T-shirts, lightweight dresses, and comfy loungewear.
  
• Double Knit Jersey/Interlock: A variation of jersey, this fabric has two layers of stitches interknit to create a thicker, more stable material. Double knit jersey will usually be high stretch across the width of the fabric with low (or no) stretch along the length. Due to its double layer, it is durable and holds shape well, making it warmer and better for more structured clothing than single knit jersey.
  
• Ribbed Knit Fabric: Also called ribbing, ribbed knit fabrics are recognized by their vertical ribs, it’s more elastic and has a high stretch across the width of the fabric with little to know stretch along the length. This fabric is often used in cuffs, collars, and as a form-fitting material for apparel due to its ability to recover easily from being stretched.
  
• French Terry: With loops on one side and a smooth face, French terry is less stretchy than jersey but is known for being cozy and warm. It’s comfortable and absorbent, making it a popular choice for loungewear and sweatshirts.
  
• Fleece: A plush knit fabric that mimics the warmth of wool. Fleece has a high stretch and is built for insulation and comfort, often used in activewear and cozy garments.
  
• Tricot: This is a warp-knit fabric which means it has fine vertical ribs on the right side and horizontal ribs on the wrong side. Tricot is stable with a slight stretch, commonly used in lingerie, sportswear, and swimwear

What to before you start sewing with knit fabrics

When sewing with knit fabrics, your approach should differ from that used with woven fabrics due to their unique stretch and behavior. These are the basics that you should be aware of before you start sewing:

1. Use a jersey or stretch needle: Use a ballpoint jersey or stretch needle to prevent damaging the fabric. These needles have a rounded tip that slips between the yarns rather than piercing them.
2. Use a zigzag or lightning bolt stitch: These are stretch stitches that will allow the fabric to maintain its stretch along the seam after it’s sewn. A straight stitch will break as soon as you try to stretch the fabric.
3. Consider using a twin needle for hems: This isn’t strictly necessary, but a twin needle creates a neat finish that allows for stretch. You can still use a regular zigzag stitch if you want, but it will be visible.
4. Pressing: Press seams gently without stretching the fabric. You may also want to use a pressing cloth to protect the fabric and keep it from stretching out.
5. Always test your setting on scraps first: I say this about all types of fabric, but it’s especially important for knits because they can be really finicky. You’ll often have to make small adjustments to your machine and stitch settings.

Knit fabric is a little frustrating to sew on a standard sewing machine. If you’re not careful, the fabric will stretch as you’re sewing it, leaving you with an ugly, wavy seam. The standard advice to fix this problem is to use a serger (or overlock machine). 

However, I don’t have one, and I can say it’s definitely possible to sew stretch fabrics with a regular sewing machine. You just need to be willing to problem-solve and test with scraps of your fabric to figure out what works.

Tips for preventing your fabric from stretching out while you’re sewing (if you’re getting wavy seams, try these):

1. Change the pressure settings on the presser foot so that it’s not clamped down as tightly.
2. Adjust the stitch length and width settings. Often a longer stitch will cause more wonky seams, but play around with the settings on your machine to see what works.
3. Adjust the top thread tension on your sewing machine. You may need to reduce the thread tension for knit fabrics.
4. Use a walking foot on your sewing machine: This is a foot that you attach to your machine that has its own feed dogs on top. This mimics an overlock and helps feed the fabric through more evenly.
5. Apply wash-away tape to the seam before sewing. This makes the fabric temporarily stable and non-stretch until you use water to wash it away.
6. Place a piece of tissue paper on top or underneath the fabric as you sew. When you finish the seam you can rip the paper away

Do you need to finish the seams of knit project? Since knit fabrics don’t fray, you technically don’t have to finish the seams. I still do because it makes the final garment a little more durable and makes the inside look a little more pristine as well. 

If you have a serger, that’s the ideal way to finish knit fabrics. However, if you’re like me and don’t have one of those handy machines, you can use an overcast foot to get a good finish.