Basics of Fabric Structure

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Whether you make your own patterns or sew from patterns you purchase, knowing the anatomy of your fabric and how to lay the pieces out will help ensure you make a great finished apparel or accessory item.   In a previous post, I walked you through the steps to make a pattern for your own sleep shorts.  The next step is obviously to cut the pattern from fabric.


Let’s go over a few key concepts and terms so when you work with fabric you make smart choices when laying out your pattern pieces.  Below the cut I will explain all those terms like lengthwise grain, crosswise grain, bias, selvage and so on in addition to providing a few tips on how to lay things out for the best success.

In most chain fabric stores (Jo Anne, Hancock, Hobby Lobby, etc), apparel fabric comes folded in half and rolled on a wide, flat cardboard bolt.  For the purpose of this post, that is how I have depicted fabric in my illustration above with a bit of fabric unrolled from the bolt.  Note: In many higher end fabric stores, discount warehouse stores, or specialty fabric stores the fabric comes flat rolled on cardboard tubes.


Let’s start by talking about woven fabrics.  Woven fabrics are made with two or more sets of yarns interlaced at right angles.  Woven fabrics are considered relatively stable and do not have a natural stretch along the lengthwise or crosswise grain unless a stretch fiber such as spandex has been introduced.


Terms for woven fabrics:
Warp a.k.a. Lengthwise Grain or Straight of Grain:
What is it?  These threads run the length of the fabric, parallel to the selvage edge.  During the weaving process, these threads run through the loom and are placed under a lot of tension.


How do I utilize it? The warp is called the lengthwise grain and straight of grain because garments hang best when those long threads hang the length of your garment as opposed to wrapping around you.  The threads are under tension during the weaving process and most of the stretch has been worked out of the threads.  This is ideal for the up/down direction of the garment because gravity won’t stretch it out over time.


Grainlines on commercial patterns and the grainlines I show you in patterning tutorials are placed so you can align the pattern pieces along the straight of grain.


Weft or Filling a.k.a. Crosswise Grain:
What is it? These threads run crosswise (perpendicular to the warp).  When they wrap around the outside warp threads, they create the selvage (finished) edge.


How do I utilize it? Filling threads are not under the same tension as the warp threads in the weaving process.  When laying out your pattern pieces, you want to think about where you might need a tiny bit of stretch when wearing.  For example, waistbands should always be placed with a crosswise grain orientation.


What is it? The finished edge of the fabric.  It is typically under tighter tension than the rest of the fabric.


How do I utilize it? You don’t.  Typically the selvage edge of fabric is under different tension or different weaving pattern so that the fabric has a nice clean edge that doesn’t snag on weaving and finishing equipment and to prevent the fabric from unraveling.  You don’t want to catch part of the selvage in what you sew because it is likely to pull or act differently than the rest of the fabric.  It might be tempting to use the selvage edge for straight lines that fall on straight of grain (like the center front of a shirt) but just say no!  It will always pull funny.


True Bias:
What is it? The true bias is a 45˚ angle from the selvage.  Woven fabric pulled on the bias has some stretch to it.  Fabric strips cut on the bias are less likely to fray than fabric cut on the straight of grain.


How do I utilize it?  Bias cut fabric is ideal for things like belts, spaghetti straps, piping trim, and seam finishes like Hong Kong finish.  Sometimes apparel items are placed so the grainline is on the bias.  Sewing a garment with a bias grainline can be very tricky as the seams can stretch and distort without careful attention.  Also, garments that are cut on the bias will have uneven hemlines due to gravity stretching the fabric.   Bias cut garments hang beautifully and are worth the effort but be sure you read a lot about how to successfully sew that type of garment before diving in.


What is it? In the context of laying out your pattern pieces, it is the direction of the fabric.  This is especially important on fabrics with prints, fabrics with textures like corduroy, velvet, terry, etc., and fabrics with a sheen such as satin.  If sewing a fabric with a nap, buy some extra fabric so all pieces can be placed the same direction on the fabric.


How do I utilize it? There are many fabric prints available and they are often created to be multi-directional fabrics.  Some fabrics prints are not.  If the fabric print is one direction, all pieces must be placed on the fabric in the same direction or the print will be upside down on some part of your garment.  Textured and shiny fabrics typically appear darker in one direction than the other.  The nap can be very subtle but you should always place pieces the same direction on those fabrics also.



Now, a bit about knit fabrics.


Knit fabric is made of a series of interlooping yarns.  Knit yarns typically stretch but the amount the fabric stretches varies based on the type of knit, the fiber content, the gauge of the yarn used.   Commercial patterns designed to be made of knit fabrics have a gauge on the outside of the pattern envelope so you can check the amount of stretch your fabric choice has against what the pattern requires.


The stretch of the knit fabric should go around your body unless specifically stated otherwise in the patterning information.  Determine the direction the fabric stretches before placing your pattern pieces to be cut out.


Also note, when cutting a pattern from knit fabric, you cannot turn some of the pattern pieces 90˚.


Coming soon – a walk through the construction of the custom fit sleep shorts!