Why detergent works

Every detergent manufacturer has secret ingredients and mixtures to produce their specific brands. Many of these ingredients can be manufactured from plants; others are petroleum-based. It is the amount of each ingredient and how they are combined that affect the cleaning ability of the detergent. Alkalies, a major component in most laundry detergents, are soluble salts and a base that reacts with an acid to neutralize it.

They are effective in removing dirt and stains from fabric without excessive rubbing. Soluble salts of an alkali metal like potassium or sodium are good grease removers. They form an emulsion of the oily or solid particles that are held in suspension in wash water to be rinsed away. The first soap and detergent makers used plant ashes to produce alkalis. Today they are chemically produced by running electricity through salt water to produce sodium hydroxide NaOH or caustic soda and potassium hydroxide KOH or caustic potash.

These are the most commonly used alkalies in soaps and detergents. Alkaline substances vary in their strength with the strongest causing burns and internal injuries if swallowed. Strong alkalies can also damage fabrics and leave clothes feeling rough to the touch.

Surfactants are one of the major components of laundry and cleaning products. They break up stains and suspend the dirt in the water to prevent the redeposition of the dirt onto the surface. Surfactants disperse dirt that normally does not dissolve in water. They work like an oil and vinegar salad dressing. They do not mix unless shaken vigorously in the bottle and they separate almost immediately afterward.

The same is true when washing clothes. Surfactants "shake up" the soil which normally does not dissolve in water, making it dispersible and able to be removed with the wash water. In anionic surfactants, the head of the molecule is negatively charged. This particular type of surfactant is very good at removing oily dirt and stains unless used in water that is full of minerals like calcium and magnesium.

The minerals keep the anionic surfactant from working properly. You'll see anionic surfactants listed as alkyl sulfates, alkyl ethoxylate sulfates, and soaps in the ingredient list. If you have hard water , you will get better cleaning results with a non-ionic surfactant. As we said earlier, surface tension is the force that prevents a blob of water on a surface from spreading out. Surface tension allows pond skaters and other insects to walk across water and also allows a pin to float.

You can demonstrate this yourself by taking a bowl of water and floating a pin on the surface. Carefully add just one drop of washing-up liquid and see what happens to the pin. It should sink immediately because the detergent molecules break apart the forces holding the water together. The pin is no longer supported and so sinks to the bottom! You can measure surface tension yourself by making your own button balance, like the one used by the famous nineteenth century home experimentalist, Agnes Pockels.

You will need:. You can set up the balance in one of two ways, as shown in the diagram above. You'll soon find out which one works best for you. The lollystick is used for the lever and the nylon thread has the advantage of not soaking up water and influencing the balance.

The piece of card can be suspended from the lollysick with the nylon thread to act as a counterbalance pan. To use your balance:. With your button balance, try measuring the surface tension of a range of liquids and comparing them. For example: cold water, salt water, warm water and soapy water. You can also try changing the size of the button used or the material it is made out of. As expected, however, it does have a few downsides.

First and foremost, you want to be careful not to get the box wet—otherwise, the product might be ruined. Pretreating also takes more effort with powders.

Instead of being able to just pour it onto the fabric, you have to first mix the powder with water separately in a bowl to make a paste. Liquid detergents were first introduced in the s. Liquid detergents have several advantages. For starters, it does not require pre-mixing—you can just use it out of the bottle. This can be a big issue for those with respiratory conditions such as allergies or asthma.

As convenient as may be, however, liquid detergents do have a few disadvantages. For instance, they typically come in plastic bottles, which is not environmentally friendly—it can take hundreds of years for the polymers to break down in the landfill. Not to mention that they generally have a shorter shelf life. Pods are popular because they are convenient. Single-dose, they do not require any measuring or guesswork; you just use the whole thing. Small and compact, they require very little storage space.

They also remain stable for longer, which means that they have a longer shelf life. Lastly, it does not create as much packaging waste. Pods are without a doubt, the most expensive type of detergent out there. Detergents are primarily surfactants , which could be produced easily from petrochemicals. Surfactants lower the surface tension of water, essentially making it 'wetter' so that it is less likely to stick to itself and more likely to interact with oil and grease.

Modern detergents contain more than surfactants. Cleaning products may also contain enzymes to degrade protein-based stains, bleaches to de-color stains and add power to cleaning agents, and blue dyes to counter yellowing.

Like soaps, detergents have hydrophobic or water-hating molecular chains and hydrophilic or water-loving components. The hydrophobic hydrocarbons are repelled by water but are attracted to oil and grease. The hydrophilic end of the same molecule means that one end of the molecule will be attracted to water, while the other side is binding to oil.

Neither detergents nor soaps accomplish anything except binding to the soil until some mechanical energy or agitation is added into the equation. Swishing the soapy water around allows the soap or detergent to pull the grime away from clothes or dishes and into the larger pool of rinse water. Rinsing washes the detergent and soil away. Warm or hot water melts fats and oils so that it is easier for the soap or detergent to dissolve the soil and pull it away into the rinse water. Detergents are similar to soap, but they are less likely to form films soap scum and are not as affected by the presence of minerals in the water hard water.