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Is Hand Soap An Acid Or Base? Know Your Detergents


Is Hand Soap An Acid Or Base

For centuries, soap has been used to clean clothes, bodies, and homes. So, why do we need to know so much more about it today? Because the way we use soap has dramatically changed since the invention of soap.

Today’s hand soaps come in many different forms and varieties. So how do you know which to choose? Knowing the pH of your hand soap is essential for many reasons. This article will give you a quick guide on the acidity and alkalinity of hand soaps.

Is Hand Soap An Acid Or Base?

In general, all hand soaps usually made from lye (from scratch) are essential, while most commercially made hand soaps are acidic.

Hand soap is considered an alkaline(base) substance because it has a high pH level. This is why soap helps remove oils and grease from the skin. However, some soaps contain mild acids that set off chemical reactions in the skin to kill bacteria.

How Does Hand Soap Work? 

Soap has been an ancient product since at least 2800 BC. Soap was once sold in locally produced bars, hard and impregnated with sodium hydroxide, at general stores in rural areas.

True soaps are rarely made in modern times because saponification can be challenging to control and make consistent. 

The “combining of fats or oils with an alkali, such as lye,” is defined as true soap or regular soap.

“Soap” comes from “saponification,” a chemical process that turns oils into alkaline salts, making them cleaner and milder. Soap can go through saponification, which has been converted into soap. 

It is a chemical reaction between an alkali and acid, often lye (sodium hydroxide) and oils. PH becomes very important in making soap to ensure you have reached saponification. This will happen when you have an equal amount of alkali (lye) and acid (oils).

Most commercial soap manufacturers use synthetic surfactants (oil-soluble) that they make from petrochemicals. These synthetic surfactants are known as “syndets.”

Syndet bars of soap have a longer shelf life than true soap bars and are easier to use, but they do not have the same cleaning ability or benefit from saponification that true soaps do.

What’s In Hand Soap?

If you look at the ingredient list on any bottle of hand soap, it usually has one of two chemicals on the label: Sodium Lauryl Sulfate or Sodium Laureth Sulfate. 

These are surfactants, chemicals that reduce the surface tension between one substance. Surfactants also have electrical charges that mix with water and oil-based substances. 

Most hand soaps are made with surfactants because they help dissolve oils, fats, and other grime that we pick up throughout the day. 

However, they also have an affinity for our skin’s natural oils and can remove them along with dirt and germs.

While it’s easy to find soaps that companies market as “gentle” or “hypoallergenic,” most of these products contain surfactants because they help clean effectively without drying out your skin. Surfactants are one of the main ingredients in hand sanitizers, too. 

Hand Soap And The pH Scale

It is essential to understand the pH scale before understanding hand soap. More acidic things have a lower pH, and more alkaline things have a higher pH.

When washing your hands, you expect them to be clean and dry. But when you’ve finished washing and drying your hands, they often feel slightly sticky or wet. Is that because of the soap you’re using?

Hand soap is a base solution, which means a pH above 7. Soap works as a surfactant and uses its positive charge to neutralize excess negative charges on the body. This is why soap helps remove dirt and oils from your hands.

However, some soaps contain mild acids (triclosan) that set off chemical reactions in the skin to kill bacteria and remove oils and grime. 

Triclosan is a very effective antimicrobial agent, and it is added to soaps because it prevents the growth of bacteria that may live on your skin. But, in recent years, there have been concerns about its safety. 

Some studies suggest that triclosan can disrupt hormone levels in animals and humans. Some also show that triclosan accumulates in tissues, and animal studies have shown that it can cause liver toxicity, dermatitis, and skin irritation.

The pH Scale

The pH scale is a measurement from 0-14, representing how acidic or alkaline a substance is. A simple way to understand pH is to compare it to its opposite basicity – or the number of bases in the substance.

A pH of 7 is neutral, with values below 7 representing an acidic solution and above 7 representing an alkaline solution. The lower the number, the more acidic it is. 

The basis of the pH scale is on a logarithmic scale. This means that each unit change equals a tenfold increase or decrease in acidity or alkalinity.

The difference between a pH of 6 and 5 is substantially more prominent than the difference between 7 and 8. The difference between 6 and 5 on the scale represents a 10-fold change in acidity. 

A change from 6 to 4 represents a 100-fold change in acidity. In other words, it takes 100 times more alkalinity to neutralize 1 unit of acid than it does to neutralize 1 unit of acid.

The pH of most soaps is around 8-10. But some soaps can be as low as 5.5 or 6, which can cause dry skin issues if used daily. Others are in the middle at 8.5.

Common Home Components, Along With Their pH Values

  • the pH of baking soda: 9.5
  • the pH of black coffee: 5
  • the pH of lemon juice and vinegar: 2
  • pH 13.5 for lye
  • the pH of bar soaps: 8–10 on average
  • the pH of the blood: 7.4
  • the pH of ammonia solution: 10.5–11.5
  • the pH of distilled water: 6.9 
  • pH 6.3–6.6 in milk, urine, and saliva
  • Commercial liquid hand soaps have an average pH of 5–6.
  • Grapefruit juice, soda pop, and tomato juice have pH values of 2.5 to 3.5.
  • pH for battery acid is less than one and close to zero

How To Test pH Of Handmade Or Store-Bought Hand Soap

When it comes to handmade soap, there’s a lot that can go wrong. Not only do you want a perfect bar, but you want a safe one. Soap has to have a specific pH balance to be safe and effective.

That’s why it’s crucial to test the pH of homemade or store-bought soap bars before use. This way, you won’t end up using something that could irritate your skin or cause an allergic reaction. 

When your skin comes into contact with an acidic substance, it can lead to dermatitis, characterized by redness, swelling, itching, and burning sensations.

Here are four ways to test the pH of handmade soap bars:

1. pH paper (or litmus paper)

There are two types of pH paper; red and blue. Put a pH strip (also known as a litmus test) in soapy water. If the blue color of the pH strip turns red, that means the soap is acidic; if the red pH strip turns blue, then the soap is alkaline.

2. Digital pH meter

You may immediately obtain a pH reading by placing a probe into a solution. A glass electrode connected to the probe is linked to an electrical gadget that measures pH levels correctly. It will typically read between 8-10.

3. Phenolphthalein

Phenolphthalein is an indicator dye used in laboratory experiments. It changes color when exposed to an acid or base. 

By adding a few drops of Phenolphthalein to a solution of soap, you can see if the pH is within an acceptable range. 

If the color changes from pink to clear, the soap is too alkaline. If it turns pink, it’s too acidic.

You can purchase Phenolphthalein at some drugstores and scientific supply stores. A simple search on the Internet will reveal numerous sources for this product.

4. Purple (red) cabbage juice

Blend cabbage strips with a bit of distilled water to get cabbage juice. Apply a few drops of cabbage juice to a bar of soap or soap solution. 

If the soap becomes blue-green, it is alkaline or basic (which means it’s safe to use). If it becomes green, it means there is an unsaponified lye present. In the presence of an acid, cabbage juice becomes red.


All hand soaps created from lye are base, whereas most commercially manufactured hand soaps are acidic. Acidic detergents, such as dish soap, are more effective at killing bacteria than basic detergents; however, that does not mean basic detergents are ineffective. 

Basic detergents are great for removing grease from dishes and hands. If you want to get the most out of your household cleaning products and save some money in the process, use an acidic detergent on dishes and a basic one on your hands.

Jacob Lindsey

Jacob is a home remodeling guru having worked over 15 years in construction in Reno, NV, mainly focused on home renovations. He likes taking ideas from his clients and making them a reality.

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