Properties of Wool Fiber:
- Market Share in Carpet: 2%
- “Hand”: Excellent
- I.D. Methods: Dissolves in chlorine bleach. Burns with a burned-hair odor to a black crumbly residue.
- Moisture Absorption: Up to 30%
- Specific Gravity: 1.32
- Resilience: Good
- Abrasion Resistance: Good
- Effects of Acids, Alkalis, and Solvents: Sensitive to acids and alkalis
- Dye Methods: Various
- Resistance to Mildew, Aging, Sunlight: Damaged by sunlight, mildew, moths, beetles. Sunlight can cause yellowing.
- Color Retention: Good
- Stain Resistance: Very Poor
- Stains/Soils Attracted to Fibers: Protein, urine, vomit, blood, meat juices
- Melt Point: None (ignites)
- Cigarette Burn Resistance: Very good
Wool is normally from fleece (sheep hair), but in antique rugs the wool can also come from other animals like goat hair, etc. At one time, wool was the primary fiber in carpet, but its cost resulted in steadily decreasing market share. Wool has several excellent qualities. It hides soil much better than synthetic fibers because it is not clear and, therefore, soil cannot be seen through it, plus it has scale edges to further hide microscopic particles of soil. It is also the preferred fiber where cigarette burns are a problem, because it does not melt. Wool’s high moisture content and protein constituents provide natural flame resistance.
Wool cells come in two different types: the paracortex and the orthcortex, which lie on opposite sides of the fiber and grow at slightly different rates. This causes a three-dimensional corkscrew pattern of coiled springs much like shock absorbers, giving wool high elasticity and a “memory” that allows the fibers to recover and resume normal dimensions. Wool fibers can be stretched up to 30 percent without rupturing and still bounce back.
Wool carpets wear well and age beautifully and have a look and feel that is unmistakably their own. However, nylon and olefin carpets will last longer in high traffic areas.
However, wool is expensive, is easily stained by nearly everything, has very poor chemical resistance making spotting and stain removal much more difficult, mildews, is attacked by carpet beetles and moths, fades easily in direct sunlight, and attracts and stubbornly holds on to protein soils such as urine, blood, and meat juices.
Use caution when using proteolytic enzyme spotters or deodorizers on wool - they are designed to attack proteins and wool is a protein.
To protect wool rugs from moths, apply Steri-Fab® and turn the rugs frequently.
Per WoolSafe North America, wool carpets and rugs should always be neutralized after cleaning to a natural pH of 4.5-5.5. Therefore, wool should be extraction cleaned with LCA®-256 followed by application of Brown Out®.