Ever since you first made friends with the rubber ducky, it’s been an important object in your everyday routine. Soap: You do use it every day, hopefully (even behind your ears). You know that it makes you feel fresh and smell clean. If you had to describe it, chances are you’d say it’s made out of something that lathers up and washes dirt away. So you think that is all you need to know about soap?

It isn’t. That slippery, shrinking bar of soap in your bathroom is not only a multi-purpose hygieneproduct that you can’t do without, but is also the object of great masquerade and can even be a health concern.

All Types

Consider, for example, how many types of soap you see advertised on television, in the magazines, or on supermarket/pharmacy shelves. Today, soap is custom-made for every complexion and is designed in virtually avary shape, size, color, and scent imaginable. There is soap for oil skin, dry skin, allergic skin, acne-prone skin, sensitive skin, normal skin, and baby skin. It can be milled, superfatted, transparent, deodorant, liquid, nonscented, or extravagantly perfumed.

Soap has come a long way since it was made from animal or vegetable fats and boiled with lye. “True soap,” as it is called today, is composed of alkaline salts and fatty acids made of coconut oil and tallow (animal fat). Most soaps are milled, which means that the mixture of fats, oils, coloring agents, and perfumes are passed through a stone or steel roller, all the excess moisture squeezed out, and the product compressed and concentrated into bars.

Soaps work as excellent cleansers because they are effective emulsifiers: They reduce the surface tension of the water, enabling it to surround and break up dirt molecules so that they can be washed away easily.

Removing More than Dirt

Yet soap can be misunderstood. According to a study conducted by Consumer Reports, soap can actually irritate the skin due to its alkaline content. By removing dirt and natural oil, soap can leave skin very dry. Some soap manufacturers add extra fat, such as lanolin, moisturizing cream, or cocoa butter, but these soaps can still leave skin dry.

Researchers have also discovered that lathering has little to do with soap’s cleaning ability. Soft water containing few minerals makes soap lather more easily, and soaps containing detergent lather more than plain soaps in hard water.

As far as best value for the money, the study showed that the best measure of the value of a soap is in how many washings you can get out of it: How long, that is, does it take the soap to dissolve. This is dependent on the soap’s form. When you pump down on a bottle of liquid soap, for example, the dispenser might serve more soap than you really need, while a squeeze container might allow you to control how much you will use — and therefore last longer.

The Lure of Perfume

Soap makers use perfume to entice you to buy their soap. The fragrance will not last long on skin after bathing or showering, the researchers concluded.

The fact is, not all soaps are for everyone. People with sensitive skin should try using a soap without a lot of additives, such as fragrances or deodorants. Dry-skinned people should look for superfatted soaps, because these remove less oil and help prevent moisture loss. People with oily skin should wash with a soap without added oils or emollients.

If you find that a soap isn’t working for you, consider the time of year and weather conditions. In the summer, when we perspire more, our skin tends to be oilier, so you might want to use different soap then. In winter, when cold weather can dry skin, we need more moisture in our soap.

Too Much is Too Much

Experts recommend not lathering up more than once when you wash, even if you have oily skin, because this can strip away natural oils. Use a soft touch, and don’t massage soap into your skin, because this may clog your pores. It’s most effective to use warm water, because extreme temperatures can irritate the skin, as well as leave traces of the soap, so rinse thoroughly. The better a soap rinses off your skin, the less likely it is to cause irritation. Use a soft washcloth to help remove dead skin cells and dirt. Be sure to rinse the cloth after each use. You needn’t worry about the pH of a soap (the numerical indication of its acidity or alkalinity). Your skin will return to its normal pH level soon after washing.

While it is important to identify your own skin type and select a soap that is right, be aware of soap’s “dirty” side.

In a study at Michigan State University Medical School, researchers found that bar soaps may be reservoirs for dangerous bacteria associated with skin infections, infections of the respiratory and urinary tracts, and botulism. They concluded that liquid soap was a preferred handwashing method. This is especially true in public restrooms.

Take a look at the wrapper on some bars of soap the next time you’re at the supermarket or drug store. Trying a new one might make a difference to the skin you’re in.