Laundry detergent is a daily necessity used in every household. Issues related to laundry detergent concern not only washing effectiveness but also health and environmental protection. Understanding some basic knowledge can achieve twice the result with half the effort—laundry detergent is a daily necessity used in every household. However, such a common detergent is not used properly by everyone. Problems related to laundry detergent involve washing effectiveness, health, and environmental protection. Therefore, one must be cautious when choosing laundry detergent and master some "tips" when using it to achieve better results.
Medical guidance / Professor Xue Zhonghua, Institute of Fine Chemicals, East China University of Science and Technology 
Enzyme-added laundry detergent cannot be used to wash silk
Common questions: How to choose laundry detergent to remove difficult stains such as oil, blood, rust, and paint?
Answer: For specific stains, laundry detergents usually add protease, amylase, lipase, and cellulase to enhance washing effects. Protease catalyzes the hydrolysis of meat stains, sweat stains, milk stains, blood stains, etc.; amylase catalyzes the hydrolysis of chocolate, mashed potatoes, rice, and other stains; lipase effectively breaks down various animal and vegetable oils and human sebaceous gland secretions; cellulase removes fiber fuzz on fabric surfaces, achieving color protection, softening, and renewal effects. Previously, single protease was mostly used, but now compound enzymes are generally used. The blue or red granules in laundry detergent are enzymes. Some companies use enzymes of poor quality and insufficient quantity, affecting washing effects, so consumers should choose well-known brand detergents. Removing rust and paint or dye stains requires certain conditions and is difficult; it is best to take them to a laundry shop. Consumers should note that enzyme-added laundry detergent cannot be used to wash silk or wool fabrics containing protein fibers because enzymes can damage the protein fiber structure, affecting the strength and luster of silk and wool fabrics. Soap or detergents specially designed for silk and wool fabrics can be used instead.
"Cold water quick effect" exaggerated advertising
Common questions: Some laundry detergents claim "cold water quick effect." What is the most suitable temperature for washing clothes with laundry detergent?
Answer: The claim of "cold water quick effect" violates chemical principles and is likely exaggerated advertising. Generally speaking, the higher the temperature, the stronger the dissolving and penetrating power of surfactants, enzymes, and additives, and the faster the stain removal. In cold water, enzymes and other active substances are not well activated, so there is no quick effect. In Europe, the default temperature for fully automatic washing machines is 40°C, which is the optimal temperature for enzymes and other active substances to react chemically and dissolve. In China, from an energy-saving perspective, the automatic washing machine temperature is generally 30°C. Of course, washing at too high a temperature is also not good; high temperatures can cause protein stains to coagulate and significantly reduce enzyme activity, making it harder to clean.
It is best to choose phosphate-free laundry detergent
Common questions: Many laundry detergents are labeled "phosphate-free" or "no phosphate." What are the harms and functions of phosphate?
Answer: Phosphate-containing laundry detergents are one of the main sources of phosphate pollution in domestic sewage. Phosphates cause water eutrophication, leading to water turbidity, massive fish deaths, and eutrophic water is unsuitable for human and animal consumption. However, the phosphate added in laundry detergent is sodium tripolyphosphate (commonly known as "pentasodium"), which can chelate calcium and magnesium ions in water, soften hard water, provide alkaline buffering, disperse suspended dirt, and enhance washing efficiency. Due to national requirements for "phosphate-free" laundry detergents, companies generally use 4A zeolite combined with appropriate polymers or layered silicates to replace phosphates. However, phosphate substitutes have weaker chelating and enhancing effects than sodium tripolyphosphate and are more expensive, which is why many detergent companies still quietly use sodium tripolyphosphate. According to incomplete statistics, phosphate-free laundry detergents certified by the national environmental label account for less than 5% of total production in China. To purify our living environment, phosphate-free, benzene-free, and fluorescent agent-free laundry detergents should be developed.
After spraying collar cleaner, wait 3 minutes
Common questions: What is special about "collar cleaner"? How to use it?
Answer: "Collar cleaner" products are mainly liquid and, besides ordinary detergent active ingredients, contain a high amount of alkaline protease, which has good decomposition ability for grease and sweat stains. Products in aluminum alloy cans perform better than those with plastic nozzles because the sprayed detergent mist can quickly disperse and penetrate the fabric surface. However, when using, note: ① Spray directly on the clothes to be washed, then let it sit for 3–5 minutes. ② Put the sprayed clothes into water containing laundry detergent, with water temperature around 40°C. ③ Since silk and wool are protein fibers, protease can also affect them, causing color or fiber damage, so be cautious when using collar cleaner on such clothes.
Concentrated laundry detergent uses less amount
Common questions: Are "high concentration" or "super concentrated" laundry detergents more effective?
Answer: Concentrated laundry detergent is a product that brings convenience to consumers. For the same amount of laundry, concentrated detergent can be used in smaller quantities, and the washing effect is not significantly different from ordinary products. Well-known brands generally produce higher-quality concentrated detergents.
However, some products on the market claiming to be "high concentration" have active ingredient content only slightly above the national standard, not truly high concentration or high content, misleading consumers, yet priced higher than similar products. Therefore, consumers should choose concentrated laundry detergents from well-known brands.
