Tuesday, February 18, 2014

Fabric 101: Protein Fibers [Part 3]

Fabric 101 - It Comes Naturally: Protein Fibers

Protein Fibers - All protein fibers are made up of amino acids. While wool and silk have similarities, they do exhibit differences because they have different molecular and physical structures.

Protein fibers are hygroscopic - this means that they will absorb moisture, but you won't feel wet (like you do in a cotton shirt). Skin temperature changes are less noticeable when you are wearing protein fibers.
Photo from theselfsufficientliving.com
Wool's fiber properties are unparalleled, and is really in a class of its own. In fact, no man-made fiber mimics all the amazing properties of wool!

Let's chat a bit about why wool is so damn itchy. Wool is like our hair - you cut it, it grows, you cut it, it grows, etc. Unlike human hair, you spin the cut pieces together to create yarn in order to make clothes (at least, I hope you aren't making clothes out of human hair). The below graphic shows this process - the sheep's wool starts with a nice pointy end. However, the first shearing creates a harsh cut edge. Lamb's wool is more desirable because it is 50% less scratchy, and significantly softer (making it way more expensive). Looking at the last illustration, you can see that there are two cut edges - this makes itchy clothes.

However, you can decrease the itch if you have longer wool fibers (longer fibers = less ends = less itch) and finer fibers (smaller cuticles [we will get there in a moment]).

Merino wool is the highest quality of sheep's wool. The finer quality Merino wool is usually from sheep raised in New Zealand. This wool is very fine and its length is between 2.5 to 5 inches long. Merino wool has a nice luster, and the higher the quality, the more lightweight the garment. Since wool has such great heat retention this means you can stay warm without wearing a bulky sweater!

One important thing to note about wool is that it shrinks when wet. The wool's cuticle (the scales in the picture below), when wet and agitated, will open and then interlock at the edges with adjacent fibers. This doesn't stop after the first few times the process happens - if this processes is repeated, the garment can eventually shrink to half its size! This is called felting.

Interesting fact: Most wool outerwear is felted to some degree. Felting draws the fibers closer together and makes a garment more wind and water resistant! It is important to note that wool is 40% weaker when wet.

Photo from ymmvreviews.com

Specialty wools found in clothing are: Alpaca (from the camel family), Mohair (from the goat family), Angora (from the rabbit family), and Cashmere (from the goat family).

Alpaca is a soft, naturally silky, and warmer than wool.
Mohair has long fibers and is shiny and bright.
Angora has short fibers, is very smooth, and needs to be woven with other wool in order to be spun.

Another interesting fact: Mohair is from the Angora goat and Angora is from the Angora rabbit.

Cashmere is from the cashmere goat that lives in Asia. The fibers are soft and warm and is the innercoat of the goat. The outercoat is coarse and is hand-separated from the innercoat. The remaining amount of wool is minimal, but is of high quality and has very fine scales.

Silk is the other important protein fiber. It is the only natural fiber that can be in filament form (remember the image in my first post?). This means that silk can be woven to be very sheer and very shiny. Silk is expensive and difficult to care for, but it dyes well and has a beautiful luster and drape. Over 50% of production happens in China, and silk is 15-20% weaker when wet.

Interesting fact: One cocoon can produce around 1,000 yards of filament silk!
Photo from wildfibres.co.uk

In order to produce the filament fiber, the silk worm has to be killed. If the worm emerges from the cocoon, the fiber is cut and can only be used in staple form - this means it is more bulky and has a duller luster.

IF YOU ONLY REMEMBER ONE THING, REMEMBER THIS: Silk and satin are not the same thing! Silk is a fiber and satin is a weave. You can make satin with silk, but you can also make satin with polyester. Silk can be woven or knit in many different ways.