Cleaning
Cleaning
The Cleaning domain tests how soils are classified and removed from carpet, upholstery, hard surfaces, and contents without damaging the material. Expect questions on cleaning chemistry, the four cleaning factors, method selection, stain removal, and residue control.
Core rules
- Soil types: soluble soils (sugars, salts), insoluble particulate (sand, soot), combined soils (grease plus particulate), and special stains (tannin, protein, dye, ink). Dry soil removal comes first; fine particulate calls for HEPA vacuuming.
- Four factors (TACT): temperature, agitation, chemical concentration, and dwell time. Raising one generally lets you lower another, but exceeding a material’s tolerance causes shrinkage, felting, dye bleed, or delamination.
- Chemistry: surfactants lower surface tension; builders soften water; solvents dissolve oils; acids dissolve mineral scale; alkalis saponify fats. Wool and silk are acid-sensitive; high pH can damage keratin and bleed acid dyes. Cellulosics may yellow or shrink. Always test in an inconspicuous area.
- Method choice: hot water extraction (HWE) for deep soil in carpet; low-moisture methods (bonnet, encapsulation, dry foam) where fast drying is required; dry soil removal before any wet method. Rinse to remove detergent residue because residue attracts soil.
Worked example
A wool area rug has a red wine stain. Wine is a dye/tannin stain; on wool, high pH, heat, and aggressive agitation can set the dye and felt the fibers. Reasoning: test a mild reducing agent (sodium metabisulfite) in an inconspicuous area; apply with low agitation and short dwell; blot, rinse with a dilute acid rinse, and dry quickly with air movement. Do not use chlorine bleach or a strong alkaline spotter on wool. If the stain remains after one careful attempt, stop and refer to a specialist rather than risk color loss.
Traps that cost marks
- Treating every stain with the same high-pH spotter; wool and silk are easily damaged.
- Over-wetting carpet or upholstery, which can delaminate backing, shrink fabric, or feed mold.
- Skipping dry soil removal, so particulate turns into mud and wicks back.
- Mixing cleaning chemicals, especially chlorine bleach with ammonia or acids, which can release toxic gas.
- Leaving detergent residue that causes rapid re-soiling.