Fibers, Fabrics, and Identification
What the exam tests
This domain checks whether you can name the fiber, predict how it reacts to water, heat, acid, alkali, and solvent, and read a fabric's construction before choosing a method. Identification is practical: a wrong call on rayon or acetate can turn a routine clean into shrinkage, bleeding, or a dissolved backing.
Fiber families and weak points
- Cellulosics (cotton, linen, rayon/viscose). Rayon can lose 30–50% of its strength when wet; linen wrinkles and can shrink; cotton tolerates mild alkali but is damaged by chlorine bleach and prolonged wetting.
- Protein fibers (wool, silk). Wool felts under heat, moisture, and agitation and prefers neutral-to-acid pH (roughly 4.5–6.5). Silk water-spots and loses luster with strong alkali.
- Synthetics (nylon, polyester, acrylic, olefin, acetate). Nylon is strong but harmed by chlorine bleach and some acid dyes; acetate is solvent-safe but dissolves in acetone; olefin is oleophilic, so oil stains wick; polyester is heat-sensitive and oil-loving.
- Blends. Clean for the most sensitive fiber in the blend.
Construction clues
Read weave (plain, twill, satin), pile (velvet, plush), knit, and backing. Long floats and loose twist snag; cut pile crushes and shows traffic; backing and sizing can bleed or brown.
Worked example
A red loose cushion cover is unknown. Burn test: self-extinguishing, hard ash bead, faint chemical odor, suggesting polyester rather than cotton. Float test: sinks slowly. Solvent test on a hidden seam: no color transfer, no dissolve. Water test: dye bleeds and face fibers relax. Decision: solvent-based low-moisture cleaning, not hot water extraction.
Traps
Assuming 'synthetic' means water-safe; testing on the face instead of a hidden seam; ignoring backing and zipper; trusting a cleaning code without a test; calling acetate 'rayon' and using an acetone spotter.