FASH 290 Classes # 5&6 Boardnotes: Natural Protein Fibers (wool, specialty wools, silk) –chapter 5 Table: 5-1
Natural protein fibers are of animal origin: wool specialty wools (hair & fur of animals), & silk (secretion of silk caterpillar). These are
luxury fibers today.
Silk and wool differ in chemical composition & physical structure but both are protein fibers. Protein wool is keratin, while
protein silk is fibroin. Wool molecule is bulkier & less compact than the silk molecule.
Keratin: wool (protein found in fingernails, horns, hooves, human hair.
Hygroscopic: (all protein fibers share this) absorb moisture without feeling wet.
Protein fibers have various amino acids: that have been formed in nature into polypeptide chains w/high molecular weigths, containing
carbon (C), hydrogen (H), oxygen (O), & nitrogen (N). they are amphoteric =have both acidic/basic reactive groups.
- Complex fiber: we have shared chemistry w/wool so we can be allergic to it.
- Wool’s combined properties are not equaled by any manufactured fiber: ability to be shaped by heat & moisture, good moisture
absorption without feeling wet, excellent heat retention, water repellency, feltability, & flame-retardancy.
Australia 22.5%, New Zealand 18.8%, China 18.8%, Eastern Europe 10%, USA ranked 10
•18-40 microns diameter range
•Merino sheep – produces most valuable wool!! ancient breed, 15-20 lbs of fleece, no kemp - Australia 43% of all Merino wool.
•Raw/Grease wool: newly removed wool; contains between 30-70% by weight of impurities: sand, dirt, grease, etc.
•Lanolin: grease removed from wool is purified to this and used in creams, cosmetics, soaps, and ointments.
•Scoured/clean wool: wool after dirt, grease, sand has been removed.
•Pulled wool -mutton
•Shoddy wool – from used clothing and rags
•Lamb’s wool -first cutting, animals less than 7 months old
•Virgin wool – never been processed before.
•Medulla: microscopic honeycomb-like core containing air spaces that increase the insulating power of the fiber.
•Cortex - main part of fiber. Made up of long, flattened, tapered cells w/a nucleus near the center. In natural colored wools, the cortial
cells contain melanin ( a colored pigment). Bicomponent – two components: one side of fiber swells more than other side, decreasing fiber’s natural crimp. When fiber dries,
•Cuticle – the cuticle consists of an epicuticle & a dense non-fibrous layer of scales.
•Felting (interlocking of scales)
•Low tenacity (and looses 40% wet)
•Good flexibility (bends 20,000 x’s vs. 3,000 for cotto