UPMSP Vocational Laundry & Dyeing key terms

A washing step that removes natural waxes, oils, pectins and dirt from greige fabric or yarn using soap or detergent with alkali, so the material absorbs water evenly before bleaching or dyeing.

A chemical treatment, usually with hydrogen peroxide or sodium hypochlorite, that destroys natural colouring matter in fibre to produce a white or uniformly pale base before dyeing.

Treating cotton under tension with strong caustic soda, which swells the fibre, increases lustre, strength and dye uptake, and improves dimensional stability of the finished fabric.

Fabric in its raw, unfinished state straight from the loom or knitting machine, still containing sizing, natural waxes and impurities, and not yet scoured, bleached, dyed or finished.

A starch or synthetic coating applied to warp yarns before weaving to reduce breakage; it stiffens the fabric and must be removed in desizing before wet processing or dyeing.

The process of removing sizing material from woven fabric, using enzymes, acid or oxidising agents, so that later scouring, bleaching and dyeing can act uniformly on the fibre.

The two yarn directions in woven fabric: warp yarns run lengthwise parallel to the selvedge, weft yarns run crosswise. Their count and crimp affect strength, shrinkage and drape.

The tightly woven self-finished edge running along both lengthwise sides of a woven fabric, which prevents yarns from unravelling and marks the warp direction.

The diagonal direction of a woven fabric at about 45 degrees to the warp and weft; bias-cut pieces stretch easily and can distort during washing or pressing.

The number of warp and weft yarns per square inch or per centimetre of woven fabric; a higher count generally gives a finer, denser and smoother cloth.

The mass of a fabric expressed per unit area, commonly grams per square metre (GSM); it guides choices about wash action, drying and pressing temperature.

A simple identification method in which a small fibre sample is burned and the flame behaviour, odour and ash are observed: cotton smells of paper, wool of burnt hair, synthetics melt into beads.

Determining what a textile is made of, using burn tests, solubility tests, microscopy or label information, so that washing, bleaching and dyeing methods suit the material.

A synthetic fibre such as polyester, nylon or acrylic that softens and melts when heated, so it must be washed and ironed at low temperature to avoid permanent shine or holes.

Localised removal of a stain from a garment using a spotting table, spatula, brush and small quantities of reagents, working from the outside of the stain inwards.

Grouping stains by their chemical nature, such as protein, tannin, oil, dye or rust, so that the correct reagent and sequence of treatment can be selected safely.

A stain of animal or food origin such as blood, egg, milk or gravy; it must be treated in cool water because hot water sets the protein and makes removal much harder.

A vegetable-based stain from tea, coffee, fruit juice or wine, usually removed with a mild acid such as acetic acid followed by washing, and never with chlorine bleach.

Stain removal using organic solvents rather than water, suited to grease, oil and paint stains on dry-cleanable fabrics; the area is dried quickly to prevent rings.

Light, repeated tapping of a stain with a brush or spatula during spotting to loosen dirt and help the reagent penetrate, without rubbing the fabric surface and causing damage.

The mechanical movement of goods through wash liquor in a machine or by hand; it loosens soil but too much agitation causes felting, pilling and wear.

A programmed sequence of fill, wash, drain, rinse and spin stages; the choice of cycle sets the time, temperature and agitation suitable for the fabric type.

The rate in revolutions per minute at which the drum extracts water from goods; higher speeds remove more water but increase creasing and the risk of damage to delicate fabrics.

A machine setting with a longer wash, higher temperature and stronger agitation designed for cotton and linen articles that can withstand robust mechanical action.

A gentle machine setting with reduced agitation, lower temperature and slow spin, used for silk, wool, lace and other fragile articles that tangle or distort easily.

The active molecule in soap and detergent that has a water-loving head and an oil-loving tail, allowing it to lift grease and soil from fibre and hold it in the wash liquor.

A formulated cleaning product containing surfactants plus builders, enzymes and brighteners, which works effectively in hard water and is available as powder, liquid or tablet.

A cleaning agent made by reacting fat or oil with alkali; it cleans well in soft water but forms scum with hard water minerals, which can grey fabrics.

A detergent ingredient such as sodium carbonate or zeolite that softens water by binding calcium and magnesium ions, and helps keep removed soil suspended in the wash bath.

Water containing dissolved calcium and magnesium salts that reduce lather, waste detergent and can leave grey deposits or scum on fabrics and inside washing machines.

A fluorescent dye added to detergent that absorbs ultraviolet light and re-emits blue light, making white fabrics appear brighter without chemically bleaching them.

The soleplate heat setting chosen for a fabric; synthetics need low heat, wool and silk medium, cotton and linen high, and overheating causes shine, scorching or melting.

Applying heat, moisture and pressure with an iron or press to smooth fabric, set creases or shape a garment; correct support and movement prevent shine and distortion.

Using steam, with or without pressure, to relax fibres, remove wrinkles and shape garments on a form or table, often used for wool, suits and delicate items.

A dye that has a direct chemical affinity for the fibre and needs no mordant, such as direct dyes on cotton or disperse dyes on polyester; applied from an aqueous bath.

A metal salt, such as alum, applied to fibre before dyeing to fix the dye by forming a chemical bridge, improving colour fastness and sometimes altering the shade.

A finely dispersed, water-insoluble dye used mainly on polyester and other synthetics, applied at high temperature or with a carrier so the dye enters the fibre.

The resistance of a dyed colour to fading or bleeding during washing, light exposure, rubbing, perspiration or pressing; it is graded and stated on care information.

A permanently attached label giving washing, bleaching, drying, ironing and dry-cleaning instructions through standard symbols and words, which the laundry must follow.