The Gentle Science Of Laundry Detergent

In this calming episode, Benjamin Boster explores the subtle world of laundry detergent—how tiny soap molecules lift away the day’s dust and leave fabrics soft and fresh. We’ll drift through the history, chemistry, and quiet rituals of washing, all in a soothing tone designed to relax your mind. Happy sleeping!

Transcript

Welcome to the I Can't Sleep Podcast where I help you drift off one fact at a time.

I'm your host Benjamin Boster.

Today's episode is about laundry detergent.

Remember to follow the show so you never miss an episode.

Laundry detergent is a type of detergent or cleaning agent used for cleaning dirty laundry or clothes.

Laundry detergent is manufactured in powder,

Washing powder,

And liquid form.

While powdered and liquid detergents hold roughly equal share of the worldwide laundry detergent market in terms of value,

Powdered detergents are sold twice as much compared to liquids in terms of volume.

From ancient times,

Additives were used to facilitate the mechanical washing of textile fibers with water.

The earliest recorded evidence of the production of soap-like materials dates back to around 2800 BC in ancient Babylon.

German chemical companies developed an alkyl sulfate surfactant in 1917 in response to shortages of soap ingredients during the Allied blockade of Germany during World War I.

In the 1930s,

Commercially viable routes to fatty alcohols were developed,

And these new materials were converted to their sulfate esters,

Key ingredients in the commercially important German brand FIWA produced by BASF and DREFT,

The U.

S.

Brand produced by Procter & Gamble.

Such detergents were mainly used in industry until after World War II.

By then,

New developments and the later conversion of aviation fuel plants to produce tetrapropylene used in household detergents production caused a fast growth of domestic use in the late 1940s.

Washing laundry involves removing mixed soils from fiber surfaces.

From a chemical viewpoint,

Soils can be grouped into the following.

Water-soluble soils,

Such as sugars,

Inorganic salts,

Urea,

And perspiration.

Solid particulate soils,

Such as rust,

Metal oxides,

Soot,

Carbon black,

Carbonate,

Silicates,

And humus.

Hydrophobic soils,

Such as animal fats,

Vegetable oils,

Sebum,

Mineral oil,

And grease.

Proteins such as blood,

Egg,

Milk,

And keratin from skin.

These require enzymes,

Heat,

Or alkali to hydrolyze and denature them into smaller parts before they can become removed by surfactants.

Bleachable stains,

Such as wine,

Coffee,

Tea,

Fruit juices,

And vegetable stains.

Bleaching is an oxidation reaction which turns a colored substance into a colorless one,

Which either stays on the fabric or may be easier to wash out.

Soils difficult to remove are pigments and dyes,

Fats,

Resins,

Tar,

Waxes,

And denatured protein.

Laundry detergents may contain builders,

50% by weight approximately,

Surfactants,

15%,

Bleach,

7%,

Enzymes 2%,

Soil antideposition agents,

Foam regulators,

Corrosion inhibitors,

Optical brighteners,

Dye transfer inhibitors,

Fragrances,

Dyes,

Fillers,

And formulation aids.

Builders,

Also called chelating or sequestering agents,

Are water softeners.

Most domestic water supplies contain some dissolved minerals,

Especially in hard water areas.

The metal cations present in these dissolved minerals,

Particularly calcium and magnesium ions,

Can react with surfactants to form soap scum,

Which is much less effective for cleaning and can precipitate onto both fabric and washing machine components.

Builders remove mineral ions responsible for hard water through precipitation,

Chelation,

Or ion exchange.

In addition,

They help remove soil by dispersion.

The earliest builders were sodium carbonate,

Washing soda,

And sodium silicate,

Water glass.

In the 1930s,

Phosphates,

Sodium phosphates,

And polyphosphates,

Sodium hexametaphosphate,

Were introduced.

Continuing was the introduction of phosphates,

HEDP,

ATMP,

EDTMP.

While these phosphorus-based agents were generally non-toxic,

They are now known to cause nutrient pollution,

Which can have serious environmental consequences.

As such,

They have been banned in many countries,

Leading to the development of phosphorus-free agents such as polycarboxylates,

EDTA,

NTA,

Citrates,

Trisodium citrate,

Silicates,

Sodium silicate,

Gluconic acid,

And polyacrylic acid,

Or ion exchange agents like zeolites.

Alkali builders may also enhance performance by changing the pH of the wash.

Hydrophilic fibers like cotton will naturally have a negative surface charge in water,

Whereas synthetic fibers are comparatively neutral.

The negative charge is further increased by the absorption of anionic surfactants.

With increasing pH,

Soil and fibers become more negatively charged,

Resulting in increased mutual repulsion.

The optimum pH range for good detergency is 9 to 10.

5.

Alkalis may also enhance wash performance via the saponification of fats.

Builder and surfactant work synergistically to achieve soil removal,

And the washing effect of the builder may exceed that of the surfactant.

With hydrophilic fibers like cotton,

Wool,

Polyamide,

And polyacrylonitrile,

Sodium triphosphate removes soil more effectively than a surfactant alone.

It is expected that when washing hydrophobic fibers like polyesters and polyolefins,

The effectiveness of the surfactant surpasses that of the builder.

However,

This is not the case.

Surfactants are responsible for most of the cleaning performance in laundry detergent.

They provide this by absorption and emulsification of soil into the water.

And also by reducing the water's surface tension to improve wetting.

Laundry detergents contain mostly anionic and non-ionic surfactants.

Cationic surfactants are normally incompatible with anionic detergents,

And have poor cleaning efficiency.

They are employed only for certain special effects as fabric softeners,

Antistatic agents,

And biocides.

Zwitterionic surfactants are rarely employed in laundry detergents,

Mainly for cost reasons.

Most detergents use a combination of various surfactants to balance their performance.

Until the 1950s,

Soap was the predominant surfactant in laundry detergents.

By the end of the 1950s,

So-called synthetic detergents,

Syndates,

Like branched alkylbenzene sulfonates,

Had largely replaced soap in developed countries.

Due to their poor biodegradability,

These branched alkylbenzene sulfates were replaced with linear alkylbenzene sulfates,

LAS,

In the mid-1960s.

Since the 1980s,

Alkyl sulfates such as SDS have found increasing application at the expense of LAS.

Since the 1970s,

Non-ionic surfactants,

Like alcohol ethoxylates,

Have acquired a higher share in laundry detergents.

In the 1990s,

Glucamides appeared as co-surfactants,

And alkylpolyglycosides have been used in specialty detergents for fine fabrics.

Despite the name,

Modern laundry bleaches do not include household bleach,

Sodium hypochlorite.

Laundry bleaches are typically stable adducts of hydrogen peroxide,

Such as sodium perborate and sodium percarbonate.

These are inactive as solids,

But will release hydrogen peroxide upon exposure to water.

The main targets of bleaches are oxidizable organic stains,

Which are usually of vegetable origin,

E.

G.

Chlorophyll,

Anthocyanin dyes,

Tannins,

Humic acids,

And carotenoid pigments.

Hydrogen peroxide is insufficiently active as a bleach at temperatures below 60 degrees Celsius,

Which traditionally made hot washes the norm.

The development of bleach activators in the 1970s and 1980s allowed for cooler washing temperatures to be effective.

These compounds,

Such as tetraacetylethylenediamine,

TAED,

React with hydrogen peroxide to produce peracetic acid,

Which is an even more effective bleach,

Particularly at lower temperatures.

The use of enzymes for laundry was introduced in 1913 by Otto Röhm.

The first preparation was a pancreatic extract obtained from animals,

Which was unstable against alkali and bleach.

Only in the latter part of the century,

With the availability of thermally robust bacterial enzymes,

Did this technology become mainstream.

Enzymes are required to degrade stubborn stains composed of proteins,

E.

G.

Milk,

Cocoa,

Blood,

Egg yolk,

Grass,

Fats,

E.

G.

Chocolate,

Fats,

Oils,

Starch,

E.

G.

Flour and potato stains,

And cellulose,

Damaged cotton fibrils,

Vegetable and fruit stains.

Each type of stain requires a different type of enzyme,

Proteases,

Savonase for proteins,

Lipases for greases,

Amylases for carbohydrates,

And cellulases for cellulose.

Many other ingredients are added depending on the expected circumstances of use.

Such additives modify the foaming properties of the product by their stabilizing and counteracting foam.

Other ingredients increase or decrease the viscosity of the solution,

Or solubilize other ingredients.

Corrosion inhibitors counteract damage to washing equipment.

Dye transfer inhibitors prevent dyes from one article from coloring other items.

These are generally polar water-soluble polymers,

Such as polyvinyl pyrrolidin,

To which the dyes preferentially bind.

Anti-redeposition agents,

Such as carboxymethyl cellulose,

Are used to prevent fine soil particles from reattaching to the product being cleaned.

Commercial or industrial laundries may make use of a laundry sour during the final rinse cycle to neutralize any remaining alkalized surfactants and remove acid-sensitive stains.

A number of ingredients affect aesthetic properties of the item to be cleaned,

Or the detergent itself,

Before or during use.

These agents include optical brighteners,

Fabric softeners,

And colorants.

A variety of perfumes are also components of modern detergents,

Provided that they are compatible with other components and do not affect the color of the cleaned item.

The perfumes are typically a mixture of many compounds.

Common classes include terpene alcohols and their esters,

Aromatic aldehydes,

And synthetic musks.

Worldwide,

While liquid and powder detergents hold roughly equal market share in terms of value,

Powdered laundry detergent is more widely used.

In 2018,

Sales of powder detergent measured 14 million metric tons,

Double that of liquids.

While liquid detergent is widely used in many Western countries,

Powdered detergent is popular in Africa,

India,

China,

Latin America,

And other emerging markets.

Powders also hold significant market share in Eastern Europe and in some Western European countries,

Due to their advantage over liquids in whitening clothes.

According to Desmay Balestra,

Designer and builder of chemical plants and detergent-making equipment,

Powder detergents have a 30-35% market share in Western Europe.

According to Lubrizol,

The powder detergent market is growing by 2% annually.

Phosphates in detergent became an environmental concern in the 1950s and the subject of bans in later years.

Phosphates make laundry cleaner,

But also cause eutrophication,

Particularly with poor wastewater treatment.

In 2013,

An academic study of fragranced laundry products found more than 25 VOCs emitted from dryer vents,

With the highest concentrations of acetaldehyde,

Acetone,

And ethanol.

Seven of these VOCs are classified as hazardous air pollutants,

HAPs,

And two as carcinogenic HAPs.

The EEC Directive 73-404-EEC stipulates an average biodegradability of at least 90% for all types of surfactants used in detergents.

The phosphate content of detergents is regulated in many countries,

E.

G.

Austria,

Germany,

Italy,

The Netherlands,

Norway,

Sweden,

Switzerland,

The United States,

Canada,

And Japan.

Laundry is the washing of clothing and other textiles,

And more broadly,

Their drying and ironing as well.

Laundry has been part of history since humans began to wear clothes,

So the methods by which different cultures have dealt with this universal human need are of interest to several branches of scholarship.

Laundry work has traditionally been highly gendered,

With the responsibility in most cultures falling to women,

Formerly known as laundresses or washerwomen.

The Industrial Revolution gradually led to mechanized solutions to laundry work,

Notably the washing machine and later the tumble dryer.

Laundry,

Like cooking and child care,

Is still done both at home and by commercial establishments outside the home.

The word laundry may refer to the clothing itself or to the place where the cleaning happens.

An individual home may have a laundry room.

A utility room includes,

But is not restricted to,

The function of washing clothes.

An apartment building or student hall of residence may have a shared laundry facility,

Such as a tsutsuga.

A stand-alone business is referred to as a self-service laundry,

Laundrette in British English,

Or laundromat in North American English.

Laundry was first done in watercourses,

Letting the water carry away the materials which could cause stains and smells.

Laundry is still done this way in the rural regions of poor countries.

Agitation helps remove the dirt,

So the laundry was rubbed,

Twisted,

Or slapped against flat rocks.

One name for this surface is a beadling stone,

Related to beadling,

A technique in the production of linen.

One name for a wooden substitute is a battling block.

The dirt was beaten out with a wooden implement,

Known as a washing paddle,

Battling stick,

Bat,

Beadle,

Or club.

Wooden or stone scrubbing surfaces set up near a water supply are gradually replaced by portable rub boards,

Eventually factory-made corrugated glass or metal washboards.

Once clean,

The clothes were wrung out,

Twisted to remove most of the water.

Then they were hung up on poles or clotheslines to air dry,

Or sometimes just spread out on clean grass,

Bushes,

Or trees.

Before the advent of the washing machine,

Laundry was often done in a communal setting.

Villages across Europe that could afford it built a wash house,

Sometimes known by the French name of Lavoir.

Water was channeled from a stream or spring and fed into a building,

Possibly just a roof with no walls.

This wash house usually contained two basins,

One for washing and the other for rinsing,

Through which the water was constantly flowing.

As well as a stone lip inclined towards the water,

Against which the wet laundry could be beaten.

Such facilities were more comfortable and convenient than washing in a watercourse.

Some Lavoirs had the wash basins at waist height,

Although others remained on the ground.

The launderers were protected to some extent from rain,

And their travel was reduced as the facilities were usually at hand in the village or at the edge of a town.

These facilities were public and available to all families,

And usually used by the entire village.

Many of these village wash houses are still standing,

Historic structures with no obvious modern purpose.

The job of doing the laundry was reserved for women who washed all their family's laundry.

Washerwomen or laundresses took in the laundry of others,

Charging by the piece.

As such,

Wash houses were an obligatory stop in many women's weekly lives,

And became a sort of institution or meeting place.

It was a women-only space,

Where they could discuss issues or simply chat.

Indeed,

This tradition is reflected in the Catalan idiom for suffrage,

Literally to do the laundry,

Which means to gossip.

European cities also had public wash houses.

The city authorities wanted to give the poor population who would otherwise not have access to laundry facilities,

The opportunity to wash their clothes.

Sometimes these facilities were combined with public baths.

The aim was to foster hygiene and thus reduce outbreaks of epidemics.

Sometimes large metal cauldrons of washed copper,

Even when not made of that metal,

Were filled with fresh water and heated over a fire,

As a hot or boiling water is more effective than cold in removing dirt.

A passer could be used to agitate clothes in a tub.

A related implement called a washing dolly is a wooden stick or mallet with an attached cluster of legs or pegs that moves the cloth through the water.

The Industrial Revolution completely transformed laundry technology.

Christina Hardiman,

In her history from the Great Exhibition of 1851,

Argues that it was the development of domestic machinery that led to women's liberation.

The mangle,

Or ringer in American English,

Was developed in the 19th century.

Two long rollers in a frame and a crank to revolve them.

A laundry worker took sopping wet clothing and cranked it through the mangle,

Compressing the cloth and expelling the excess water.

The mangle was much quicker than hand twisting.

It was a variation on the box mangle used primarily for pressing and smoothing cloth.

Meanwhile,

19th century inventors further mechanized the laundry process with various hand-operated washing machines,

To replace tedious hand rubbing against a washboard.

Most involved turning a handle to move paddles inside a tub.

Then some early 20th century machines used an electrically powered agitator.

Many of these washing machines were simply a tub on legs.

With a hand-operated mangle on top.

Later the mangle too was electrically powered.

Then replaced by a perforated double tub,

Which spun out the excess water in a spin cycle.

Laundry drying was also mechanized with clothes dryers.

Dryers were also spinning perforated tubs,

But they blew heat air rather than water.

In the late 19th and early 20th century,

Chinese immigrants to the United States and to Canada were well represented as laundry workers.

Discrimination,

Lack of English language skills and lack of capital kept Chinese immigrants out of most desirable careers.

Around 1900,

One in four ethnic Chinese men in the U.

S.

Worked in a laundry,

Typically working 10 to 16 hours a day.

Chinese people in New York City were running an estimated 3,

550 laundries at the beginning of the Great Depression.

In 1933,

The city's board of aldermen passed a law clearly intended to drive the Chinese out of the business.

Among other things,

It limited ownership of laundries to U.

S.

Citizens.

The Chinese Consolidated Benevolent Association tried fruitlessly to fix it.

But it could not fend this off,

Resulting in the formation of the openly leftist Chinese Hand Laundry Alliance,

CHLA,

Which successfully challenged this provision of the law,

Allowing Chinese laundry workers to preserve their livelihoods.

The CHLA went on to function as a more general civil rights group.

Its numbers declined strongly after it was targeted by the FBI during the Second Red Scare,

1947 to 1957.

From 1850 to 1910,

Zulu men took on the task of laundering the clothes of Europeans,

Both Boers and British.

Laundering recalled the specialist craft of hide-dressing,

In which Zulu males engaged in izin-yonga,

A prestige occupation that paid handsomely.

They created a guild structure,

Similar to a union,

To guard their conditions and wages,

Evolving into one if not indeed the most powerful group of African workmen in 19th century Natal.

In India,

Laundry was traditionally done by men.

A washerman was called a dobiwala,

And dobi became the name of their caste group.

A laundry place is generally called a dobigat.

This has given rise to place names where they work or worked.

Laundry processes include washing,

Usually with water containing detergents or other chemicals,

Agitation,

Rinsing,

Drying,

Pressing or ironing,

And folding.

The washing will sometimes be done at a temperature above room temperature to increase the activities of any chemicals used and the solubility of stains,

And high temperatures kill microorganisms that may be present on the fabric.

However,

It is advised that cotton be washed at a cooler temperature to prevent shrinking.

Many professional laundry services are present in the market,

Which offers at different price ranges.

Agitation helps remove dirt,

Which is usually mobilized by surfactants from between fibers.

However,

Due to the small size of the pores and fibers,

The stagnant core of the fibers themselves see virtually no flow.

The fibers are nevertheless rapidly cleaned by diffusivoresis,

Carrying dirt out into the clean water during the rinsing process.

Various chemicals may be used to increase the solvent power of water,

Such as the compounds in soap root or yucca root used by Native American tribes,

Or the ash lye,

Usually sodium hydroxide or potassium hydroxide,

Once widely used for soaking laundry in Europe.

Soap,

A compound made from lye and fat,

Is an ancient and common laundry aid.

Modern washing machines typically use synthetic powdered or liquid laundry detergent in place of more traditional soap.

Dry cleaning refers to any process which uses a chemical solvent other than water.

The solvent used is typically tetrachloroethylene,

Which the industry calls PERG.

It is used to clean delicate fabrics that cannot withstand the rough and tumble of a washing machine and clothes dryer.

It can also obviate labor-intensive hand washing.

In some parts of the world,

Including North America,

Apartment buildings and dormitories often have laundry rooms where residents share washing machines and dryers.

Usually,

The machines are set to run only when money is put in a coin slot.

In other parts of the world,

Including Europe,

Apartment buildings with laundry rooms are uncommon,

And each apartment may have its own washing machine.

Those without a machine at home or the use of a laundry room must either wash their clothes by hand or visit a commercial self-service laundry,

Laundromat,

Laundrette,

Or a laundry shop.

A clothes dryer,

Tumble dryer,

Drying machine,

Or simply dryer is an electric household appliance used to remove moisture from loaded clothes,

Linens,

And other textiles.

Usually after washing them in a washing machine.

In the United States and Canada,

More than 80% of all homes have clothes dryers.

The manual clothes dryer was created in 1800 by M.

Beauchamp from France.

Henry W.

Altorfer invented and patented the electric clothes dryer in 1937.

J.

Ross Moore,

A North Dakota inventor,

Designed automatic clothes dryers and published his electric dryer design in 1938.

Industrial designer Brooke Stevens designed an electric dryer with a glass window in the early 1940s.

Sometimes dryers are integrated with the washing machine in the form of washer-dryer combos,

Which are essentially a front-loading washing machine with a built-in dryer.

Or in the U.

S.

,

A laundry center,

Which mounts a dryer on top of the washing machine and combines the controls for both machines into one control panel.

Often the washer and dryer functions have different capacities,

With the dryer usually having a lower capacity than the washer.

Laundry dryers can also be top-loading,

In which the drum is loaded from the top of the machine and the drum and supports are on the left and right sides,

Rather than the more traditional front and back sides of the machine.

They can be up to 40 centimeters wide and can include removable stationary shelves for drying things,

Like stuffed toys and shoes.

Reviews

Kind of interesting! I should’ve had this on repeat as I kept waking up all night. Tonight’s another night to try to get a good nights sleep! Thank you, Benjamin! 😻😻

Amazing! Just a few moments and 🤷🏻‍♀️😴😴😴😴😴😴 I have listened to this one 3 times now and I can’t make it through it 🤭😴🙏🏼