INT-HKL-4.1.2

Sorting, Water Temperature and Wash Chemistry

Covers laundry sorting criteria, choice of water temperature, and the chemistry of detergents, enzymes, chlorine and oxygen bleach, softeners and water hardness.

Turnaround day. There is a mountain of linen, a bag of crew kit, the chef's whites, deck towels stiff with salt, and the owner's bed set. If you throw all of it in together you will get grey linen, pink shirts and a red-flagged mistake that follows you for the rest of the season. Sorting is where laundry is won.

Sorting — the six criteria

Sort by colour, fibre, soil level, texture/lint, temperature and owner.

  • Colour: whites, lights, darks, and anything new or strongly dyed (reds, indigo denim) washed separately the first few times.
  • Fibre: cotton and linen together; delicates (silk, wool, viscose) apart; synthetics apart.
  • Soil: heavily soiled deck and engineering kit never goes with guest linen, ever.
  • Lint: towels shed; they do not go with dark synthetics or bed linen.
  • Owner: owner / guest / crew laundry are kept and processed separately — this is a standing rule on most yachts.

Water temperature

Temperature Use
Cold (~20–30°C) Delicates, wool, silk, bright colours, protein stains (blood, egg, sweat) — heat sets protein permanently
Warm (~40°C) The everyday default: colours, mixed loads, light soil
Hot (~60°C) White cotton bed linen and towels, heavy soil, sanitising (60°C is the usual practical threshold for killing most vegetative bacteria and dust mites)
Very hot (90°C) Rarely used; shortens linen life significantly

Hotter is not automatically better: heat sets protein and tannin stains, shrinks cotton, felts wool and destroys elastane.

Wash chemistry

  • Detergent works by surfactants — molecules with a water-loving and an oil-loving end that lift soil into the water. Dose to the machine and the water hardness; over-dosing leaves residue, which makes linen grey, stiff and irritating to skin.
  • Enzymes (protease, amylase, lipase) in biological detergent break down protein, starch and fat stains. Effective at low/medium temperatures, but enzymes attack protein fibres — never use biological detergent on wool or silk.
  • Chlorine bleach (sodium hypochlorite): only on white cotton/linen. It yellows and weakens wool and silk, damages elastane, ruins colours, and corrodes stainless. Never mix with acid or ammonia.
  • Oxygen bleach (percarbonate/peroxide): colour-safe, gentler, works best warm; the right choice for most yacht whites and for brightening.
  • Fabric softener coats fibres. It reduces the absorbency of towels and the wicking of technical fabrics, and it must never be used on microfibre — it clogs the fibre and destroys the cloth.
  • Water hardness matters: hard water reduces detergent effectiveness and deposits scale in the machine.

Onboard Notes

  • Empty pockets and close zips and hooks — a hook will destroy a run of guest linen in one cycle.
  • Do not overload. Fabric needs room to move or nothing gets clean and rinsing fails.
  • Rinse salt out of swimwear and deck towels in fresh water first; salt crystals abrade fibres and hold moisture.
  • Fresh water is finite. Run full, correctly sorted loads and use the machine's eco/short options where the load allows.

Practice questions

5 questions
recallcore

recall · core

What are the sorting criteria for laundry onboard?

recallcore

recall · core

When would you use cold, warm and hot water, and why is hotter not always better?

recallcore

recall · core

What is the difference between chlorine bleach and oxygen bleach?

scenariostretch

scenario · stretch

Guest bed linen is coming out of the wash grey, stiff and slightly rough. What are the likely causes?

oralstretch

oral · stretch

Explain how detergent actually works, and why biological detergent is banned on some items.

Independent study. xplor is not an IAMI- or PYA-accredited GUEST training provider. This course covers the ground assessed in GUEST Unit 32; it awards no GUEST unit, certificate or Certificate of Competency and does not count toward one.

School