Home Care & Detergents

A builder removes or ties up the calcium and magnesium in hard water so the surfactant can clean instead of forming scum. Sodium tripolyphosphate sequesters hardness and helps disperse soil; soda ash precipitates hardness and supplies alkalinity; sodium silicate adds alkalinity, protects washing-machine metal and gives powder granules structure. The right builder level depends on the water hardness in the markets where the detergent will be sold.

Sodium percarbonate is an oxygen bleach: in water it releases hydrogen peroxide, is gentle on most coloured fabrics and suits laundry powders and stain removers, but it works best in warm water, around 50 °C and above, unless an activator such as TAED is added. Sodium hypochlorite is a chlorine bleach that works in cold water and also disinfects, but it can strip colour and must never be mixed with acids or ammonia-based cleaners.

An optical brightener such as CBS-X absorbs invisible ultraviolet light, around 340-370 nm, and re-emits it as visible blue light, around 420-470 nm, so fabric reflects more light and looks brighter white. Ultramarine blue is a blue pigment that adds no light: it masks yellowing by absorbing part of the longer-wavelength end of the spectrum. Many detergent powders and bars use both, with the brightener doing most of the whitening.

Choose by the soil and the surface. Hydrochloric acid is fast on heavy scale but fumes and attacks metal fittings. Sulphamic acid is a solid that gives off no fumes, dissolves limescale well and can be packed as a powder or a liquid. Phosphoric acid removes scale and light rust, oxalic acid lifts rust and yellow stains, and citric acid suits milder kitchen and bathroom cleaners. Keep acids off marble, and never mix acid cleaners with bleach.