Tuesday, June 17, 2014

Fabric Basics

A textile arts blag would be remiss if it didn't start with a basic discussion about textiles. This post is a crash course on understanding fabric properties, which will help you make the right choices later when you're working on sewing projects.

1. Right side and wrong side
Fabric usually has a right side and a wrong side. The right side is the one you generally want facing outside--prints, for example, have a right side (the patterned side) and a wrong side (the side where you can't see the pattern). The photo above shows both, with the selvage at the bottom.

2. Grain lines
Fabric runs in two directions, or grainslengthwise and crosswise. The outermost lengthwise threads are called the selvage, and fabric on a bolt is usually folded in half lengthwise, parallel to these edges. The crosswise threads run perpendicular to the selvage. In woven fabrics, because the crosswise threads go over and under the warp threads, they have a little bit of stretch, though not much.

Grainlines are important because they severely affect the end result of your sewing project; even when cut, the threads are oriented in a specific direction. When you cut out a commercial pattern, the various arrows (example below) on the pieces tell you how they ought to be oriented on the fabric. The grainline almost always refers to the lengthwise direction.

In basic skirts and shirts, that lengthwise grain runs from top to bottom in the garment. Crosswise grains are can skew to the left or right if you aren't careful about how you cut the fabric. If you aren't following a commercial pattern, it's still important to be aware of grainlines, and to make sure that your garment pieces are at least following the same direction.

3. Bias
It's also common to cut fabric along the bias (like above), or at a 45º angle to the lengthwise and crosswise grains. In woven fabrics, which do not stretch across their length or width, they will stretch along the bias.

4. Nap
No, not nap time, though that does sound nice! Fabrics like suede or velvet have a nap: run your hand in one direction, and the fibres that stick above the surface will lean in that direction. It's especially important to make sure that your cut pieces have matching alignment, or else you may end up with obviously different panels.

Here's a piece of minky. At the top left, I've messed up the nap a bit. At the bottom right, I put a lump underneath, so you can see the differences depending on how the light falls on the fabric.

This is also true for prints or designs on fabric. You can manipulate the grainline to get different pattern interactions, though!

5. Fabric types
At the most basic level, there are three categories of fabric: wovensknits, and non-wovens, determined by how their threads are arranged. In the next couple of posts, I'm going to cover woven and knit fabrics, so stay tuned!