Turn over a box of washing powder or a bottle of glass cleaner and you'll find words like phosphates, ammonia and optical brighteners. They can sound alarming, but each one has a specific, well-understood job.
This guide answers what do optical brighteners do, explains why phosphates in detergent are limited in Great Britain, and shows where ammonia earns its place. It's a fair look at conventional chemistry, so you can read a label and pick the right product for the job.
Detergent ingredients explained: four jobs in one box
Most cleaning products are a team of ingredients, each with its own job. Once you know the jobs, the label makes sense.
- Surfactants loosen oily soil and hold it in the water so it rinses away.
- Builders, such as phosphates, soften the water so the surfactants can work.
- Alkalis, such as ammonia or washing soda, break down grease and fatty soil.
- Optical brighteners change how white fabric looks in daylight. They don't remove soil.
Surfactants can come from petrochemical or plant-derived sources. We compare the two approaches here:
Plant-based vs conventional stain removers
Phosphates in detergent: what builders do
Hard water carries dissolved calcium and magnesium. These minerals tie up surfactants and bind to soil, so less of the detergent is free to clean and dirt can settle back onto fabric.
A builder locks those minerals away. Sodium tripolyphosphate was long the classic builder, because it holds calcium and magnesium very effectively and helps keep loosened soil suspended in the wash.
Why phosphate limits exist
Phosphorus is a plant nutrient. Too much of it in rivers and lakes feeds algal growth, a problem called eutrophication, and it costs money to remove at waste water treatment works.
That's why the law limits phosphorus in household detergents. In Great Britain, the retained Detergents Regulation sets these rules:
- Consumer laundry detergents can't be sold if the recommended dose for a standard wash contains 0.5 g or more of phosphorus in total (since 30 June 2013).
- Consumer automatic dishwasher detergents can't be sold if a standard dose contains 0.3 g or more of phosphorus (since 1 January 2017).
- The limits cover all phosphorus compounds, not just phosphates, but leave room for the small amounts of phosphonates that modern formulas use.
- They apply to consumer products only. Industrial and institutional detergents aren't covered.
Detergents are only one source of phosphorus in water. Sewage and farming also contribute, so detergent limits work alongside better waste water treatment.
What replaced phosphates
Detergent makers now use other builders. Zeolites are mineral ion exchangers that swap their sodium for calcium. Citrates, polycarboxylates and sodium carbonate (washing soda) also help soften the water.
Ammonia cleaner uses: an alkaline degreaser
Household ammonia is ammonia gas dissolved in water, typically around 5–10%. It's alkaline, so it breaks down greasy, oily films, and it evaporates quickly, so it dries clear without streaks.
That's why ammonia or ammonium compounds turn up in:
- glass and mirror cleaners
- some all-purpose and hard-surface cleaners
- some oven and hob cleaners
It has limits. Extension guides warn that alkalis can darken aluminium and damage linoleum and oil-based paint, so use a mild solution, rinse well and wear gloves. Open a window, as the vapour irritates eyes and airways.
Never mix ammonia with bleach
UKHSA warns that mixing bleach (sodium hypochlorite) with an ammonia-based cleaner produces chloramines, which strongly irritate the airways. Glass cleaners are a common, easily forgotten source of ammonia.
- Use one cleaning product at a time.
- Rinse the surface with clean water before you switch to another product.
- Keep products in their original containers and follow the label.
- Open a window while you clean.
- If you mix products by accident and feel unwell, leave the room straight away. Fire services advise calling 999.
For how alkalis and acids differ, read:
pH of cleaning products explained
For more on bleach chemistry and safety, read:
Chlorine bleach vs oxygen bleach
What do optical brighteners do?
Optical brighteners, also called fluorescent whitening agents, absorb invisible ultraviolet light and give it back as visible blue light. That process is called fluorescence.
White fabric tends to look yellowish over time, because it reflects less blue light. The blue glow from a brightener cancels out that yellow cast, so whites look whiter and brighter in daylight.
An optical effect, not a clean
Brighteners are made to attach to the fibre and stay there after rinsing. That's how they work, and it's why a white T-shirt glows under a UV torch.
- They don't remove soil or stains. The surfactants and builders do the cleaning.
- They replaced old-fashioned laundry "bluing", which hid yellowing with a faint blue tint.
- Detergent packs sold to the public must list optical brighteners whatever the amount, so you can check.
Why carpet guides say keep laundry detergent off carpet
Carpet-care guidance warns against using laundry detergent on carpet spills, because the optical brighteners in it can dye the fibre. Use a cleaner made for carpets and upholstery instead, and patch test first.
How to read a detergent label in the UK
The same Detergents Regulation sets labelling rules for detergents sold to the public.
- Phosphates, phosphonates, each type of surfactant, zeolites and several other groups added above 0.2% are shown in weight bands: less than 5%, 5–15%, 15–30%, or 30% and more.
- Optical brighteners and perfumes are listed whatever the amount.
- The pack gives a website address for the full ingredient list.
A label tells you what's in a product, not whether it suits your job. Match the product to the surface and the stain.
Where a plant-powered spot cleaner fits
A laundry detergent is built for a drum full of water. A spot cleaner works on a small area of a mat, rug or sofa that you can't put in the machine.
STAIN LIFT Ultra Strength Mat & Textile Stain Remover is a spray made for that job. It's labelled to eliminate stubborn wine, blood, oil & grime on mats and textiles. It isn't a laundry detergent, dishwasher product or glass cleaner.
- Prep: remove excess with a clean cloth.
- Apply: spray on the affected area.
- Dwell: leave for 1–2 minutes.
- Lift: work gently with a soft brush or scour sponge.
- Finish: wipe with a damp cloth and leave to air dry.
Always patch test on a hidden area first to check colour-fastness. As with any cleaner, use one product at a time on a spot.
Frequently asked questions
What do optical brighteners do in laundry detergent?
They absorb invisible ultraviolet light and re-emit it as visible blue light. That blue glow offsets the yellow cast white fabrics pick up over time, so whites look whiter and brighter in daylight. Brighteners don't remove dirt or stains; the surfactants and builders in the detergent do the cleaning.
Are phosphates banned in detergent in the UK?
Not completely. In Great Britain, consumer laundry detergents can't be sold if a standard dose contains 0.5 g or more of phosphorus, and consumer dishwasher detergents must stay under 0.3 g per standard dose. The limits aim to reduce eutrophication of rivers and lakes, and industrial and institutional detergents aren't covered.
What is ammonia used for in cleaning?
Ammonia is an alkaline degreaser that cuts greasy films on glass, mirrors, hobs and hard surfaces, and it evaporates quickly, so it dries without streaks. Use a mild solution, open a window, wear gloves and rinse well. Never mix it with bleach, because the combination produces irritating chloramine gases.
Does STAIN LIFT replace laundry detergent?
No. STAIN LIFT is a spray for spot treating mats, rugs and textiles, labelled to eliminate stubborn wine, blood, oil and grime, so keep using your usual detergent in the washing machine. On mats and textiles you can't machine wash, follow the five steps and patch test on a hidden area first.
Ready to treat the spot, not the whole wash?
Conventional ingredients each have a job: builders soften water, ammonia cuts grease and brighteners change how whites look. Pick the product made for the task in front of you.
For wine, blood, oil and grime on mats and textiles, STAIN LIFT eliminates stubborn wine, blood, oil & grime. It's plant-powered and biodegradable, with >30% plant-derived non-ionic green surfactants and vegetable extracts.
It's Made in Britain, an easy spray that revitalises fibres, and its safety data sheet shows it is not hazardous under GB CLP. It's available now; for the SDS or trade enquiries, email info@stainlift.co.uk.
