Dishwashing liquid



Dishwashing liquid (or washing-up liquid in British English), or dishwashing soap, dish detergent, and dish soap is a detergent assisting in dishwashing. Dishwashing detergents for dishwashers come in various forms like cartridges, gels, liquids, pacs, powder, and tablets.  It is usually a highly-foamy mixture of surfactants with low skin irritation that consumers primarily use for washing glasses, plates, cutleries, and cooking utensils. In addition to its primary use, dishwashing liquid also has various informal applications, like creating bubbles, clothes washing, and cleaning birds from oil spills.

Dishwashing liquid has existed for a long time with different compositions and using conditions. Currently, dishwashing liquid functions best with hot water. However, there are some special dishwashing liquids designed to work well with cold water or seawater.

History
Consumers used washing soda (sodium carbonate) for dishwashing. Sometimes, people used it in areas with hard water. People used it for dishwashing before the invention of detergents in Germany during World War I. People started to manufacture liquid detergent for dishwashing during the middle of the 20th century. Dishwashing detergent producers started production in the United States in the 1930s–1940s. Teepol, the first such in Europe, commenced production in 1942.

In 2005, dishwashing detergent retail sales totaled nearly US$10 billion worldwide.

Composition and Safety
Dishwashing liquid may contain bleach, enzymes, or rinsing aids.  The main ingredient is water; the main active ingredients are detergents. Dishwashing liquid has detergents, rather than soaps because they do not react with any minerals in the water to form soap scum. There are other thickening and stabilizing agents, as well.

Hand dishwashing detergents utilize surfactants to play the primary role in cleaning. The reduced surface tension of dishwashing water, and increasing solubility of modern surfactant mixtures, allow the water to run off the dishes very quickly. Additionally, surfactants remove grease and food particles to aid in cleaning dishes. They may also provide foam.

Other ingredients may include hydrotrope, salts, preservatives, fragrances, antibacterial ingredients and dyes. Preservatives prevent micro-organisms' proliferation within the liquid. Antibacterial ingredients make it difficult for bacteria to survive on surfaces. In 2010, the United States FDA raised health concerns over triclosan, an antibacterial substance used in some dish liquids.  Elsewhere, triclosan has been found to create problems at wastewater treatment plants, whereby it can "sabotage some sludge-processing microbes and promote drug resistance in others."  As of 2014, at least one state within the United States has banned triclosan in dishwashing liquids. 

Some dishwashing products contain phosphates. Phosphates make dishes cleaner but can also cause harmful algal bloom as the wastewater goes back to the natural environment. Because of this, many places banned this component. Phosphates can also cause harmful health effects upon skin contact.

Many dishwashing liquids contain perfume which can cause irritant or allergic contact dermatitis. It can cause hand eczema. Those with "sensitive skin" should persuade someone else to do the washing up. Recent research has found that Blackcurrant seeds are helpful for lessening the effects of allergies, due to its hydrophobicity. Surfactants that are anionic also showed promising results in preventing skin irritation.

Adding onto potential skin irritation, accidental ingestion of rinse aids (components within dishwashing tablets) can lead to vomiting.  

Some alternatives for dishwashing detergents may be homemade, using ingredients such as borax, essential oil, eucalyptus oil, leftover cooking oil, and bar soap, among others.

Surfactant design
There has been comparisons of different surfactants that reduce the surface tension of water to determine the most efficient dishwashing liquid. Lowering of surface tension helps with the cleaning processes. A study showed that anionic surfactant combined with non-ionic surfactant worked better than anionic and amphoteric surfactants combined. Another study pointed out that cationic and anionic surfactants combined worked better than non-ionic and anionic surfactants combined. Therefore, cationic and anionic surfactants work better than anionic surfactant combined with non-ionic surfactant. Anionic and amphoteric surfactants combined are the least effective out of the three.

Primary uses
Dishwashing liquid is primarily for removing food from dirty dishes and tableware.  Consumers usually scrape heavy soil (large food particles) from the dishes before using dishwashing liquid. 

Hand dishwashing
Consumers handwash dishes in the absence of a dishwashing machine when large "hard-to-clean" items are present, or through preferences. Some dishwashing liquids can harm household silvers, fine glassware, anything with gold leaf, disposable plastics, and any objects that are brass, bronze, cast iron, pewter, tin, or wood, especially under hot water and the action of a dishwasher.  Dishwashing liquid components are also harder to rinse off from rough surfaces than smooth surfaces, increasing the chance of accidental ingestion. 

Automatic dishwashing
Automatic dishwashing is when consumers use a dishwashing machine or other apparatuses. It is generally for convenience, sanitation, or personal preference. The cleaning is less reliant on the detergent's surfactants and more so on the machine's hot water as well as the detergent's builders, bleach, and enzymes. Automatic dishwashing detergents' surfactants generally have less foam to avoid disrupting the machine.

Informal uses
Reader's Digest notes it may be used to kill ants and weeds, help spread water-borne fertilizer, and wash human hair. Good Housekeeping says it can be mixed with vinegar to attract and drown fruit flies. Dishwashing detergent can clean mirrors as well as windows.
 * Twibright Labs published Pling, an open-source general-purpose cleaner for glazed, plastic, chrome, and stainless steel bathroom and kitchen surfaces. It uses dishwashing liquid as one of the active ingredients.
 * Dishwashing liquid with water and additional ingredients such as glycerin and sugar produces a bubble-blowing solution.
 * Dishwashing liquid can clean delicate clothing fabrics such as hosiery and lingerie.
 * Dishwashing liquid in a dilute solution can make decals and vinyl graphics easier to position when applying.
 * In industry, some use dishwashing liquid for inspecting equipment under pressure for leaks, such as propane fittings. They can also use dishwashing liquid for inspecting pneumatic tires for flats, as well as for quality assurance during the installation process, and as a mounting bead lubricant.
 * Dishwashing liquid can act as an ingredient in making homemade garden pest deterrents. Oregon State University's Cooperative Extension Service notes the use of dishwashing liquid to get rid of spider mites. Dish soap can also deter aphids. In some instances, the dish soap may be toxic to plant leaves and cause them to "burn". The University of Georgia noted the use of soap or dish detergent to help spread pesticide on plants, however, the institution did not recommend this method.
 * A solution of dishwashing liquid and water can remove coffee, tea, olive oil, soda and fruit juice stains from fabrics. One dishwashing liquid brand can remove stains from white or lightly colored cloth napkins.
 * Dishwashing liquid can treat birds in oil spills.
 * Dishwashing liquid can substitute for borax for activating slime
 * Dishwashing liquid can prepare a bubble bath.

Market share
Currently, market research companies like Euromonitor and Grand View Research collect data on different brands' market share.

Grand View Research gives the general global market trend. For example, for 2021, the company reported dishwashing detergent market share to be at 17.98 billion US dollars worldwide.

Euromonitor International collects market trends of many big brands like Procter and Gamble, Colgate-Palmolive, Henkel, Reckitt Benckiser, Unilever, Ajax. 

For example, according to Euromonitor International in 2013, Reckitt Benckiser held highest retail value share percentages in nine countries:  Italy (31%), Spain (29%); with Finish brand: Australia (38%), New Zealand (38%), Austria (32%), Ireland (29%), and Israel (27%); Denmark (30%) with Neophos brand; and Portugal (22%) with Calgonit brand.