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What is Bleach? - The History, Properties and Uses of Sodium Hypochlorite

Chemical Structure

Most pressure-washing businesses use "Bleach" as their main chemical to combat the dirt and grime on the outside surfaces of buildings. In order to understand why Bleach is used, it is necessary to define a few key terms.


Bleach is a colloquial term given to chemicals and cleaners of various kinds that remove stains and contain disinfectant properties. The most common chemicals referred to as "Bleach" are those with varying concentrations of Sodium Hypochlorite.

Bleach is also used as the verb "bleaching" which means "to remove the color from something" - an action that can be done with a chemical other than bleach ( or sodium hypochlorite).

Clorox - When most red-blooded Americans hear the word BLEACH, we think of CLOROX bleach. Clorox is actually the shortened name of The Clorox Company (formerly Clorox Chemical Company) headquartered in California. The Clorox Company produces many products including 'Clorox Bleach'. The brand name has become so widely known that the term "Clorox" is often used as a synonym for "Bleach". The Clorox company produces varying concentrations of Bleach with some being "regular" and some being "concentrated".

Take for example these two images below.

- The product on the left contains 6.0% Sodium Hypochlorite, and

- The image on the right contains 7.5% Sodium Hypochlorite. This is the "concentrated" formula.

Chlorine - Discovered in 1774 by Carl Wilhelm Scheele in Sweden, the yellowish-greenish gas became Element 17 on the Periodic Table of Elements. The name Chlorine comes from the Greek word χλωρός word meaning Yellowish-Green, the same term used by Mark's Gospel to describe the color of the grass Jesus commanded the audience of 5,000 to sit down on before performing the miracle of the five loaves and two fishes. Chlorine is unique on the periodic table as it has the highest electron affinity of all the elements meaning it is the strongest seeker of an electron to complete its outer shell of seven electrons.

It has a sharp, toxic smell that when whiffed is described as "burning the nose". Chlorine is a poisonous gas and is considered a "pulmonary irritant". It even has a less-than-stellar track record of being used as a chemical weapon by the Germans and British in World War 1 (1915).

Despite its toxic properties and dangerous capacities, we consume Chlorine nearly every day, albeit in a slightly different form. When Chlorine gas comes into close proximity to the soft-metal Sodium, Sodium Chloride is formed (aka "Table Salt"). Sodium, with only one electron in its outer shell, is very benevolent and jumps at the opportunity to help Chlorine complete its conquest for a perfect eight electrons in its outer layer. Chlorine's affinity for metals in part explains why it is so highly corrosive to them.

Sodium Hydroxide - (NaOH) also known as Lye, Caustic Soda, and Salt Brine, this compound is most commonly produced by Electrolysis of NaCl.

Once Hydrogen gas is removed, Chlorine gas is then "bubbled into" or "combined with" the Sodium Hydroxide producing NaClO, Sodium Hypochlorite, or Bleach, all terms for the same thing.

For more information on Electrolysis and the production of Sodium Hydroxide check out this amazing video:

Sodium Hypochlorite - (NaClO) or what we commonly know as "Bleach".

Since Chlorine occurs naturally as a gas, it makes it very difficult to use it as a cleaning agent.

Sodium Hydroxide

When the Hydrogen bond is broken by electrolysis and Chlorine gas is bound to Sodium Hydroxide you get Sodium Hypochlorite

Sodium Hypochlorite

There are at least 5 ways I could find to produce Sodium Hypochlorite:

  1. Chlorination of Soda (1789)

  2. From Calcium Hypochlorite (used after WW 1)

  3. Electrolysis of Brine (started at the end of the 19th century)

  4. From Hypochlorous Acid and Soda (1966)

  5. From Ozone and Salt

The third method is the most commonly used today and on a large commercial scale the process is called the "Hooker's process".

This process involves the following chemical development:

That is to say, with the right equipment, you can turn table salt and water (or Normal Saline for those in the medical field) into Bleach. But if you are like me, you might wonder how this whole cleaning/bleaching/disinfectant/discoloration industry began. For that, we must go back a few thousand years.

History of Bleach

There are claims that Bleach is thought to have been known back to 3000 BC when a solution made by mixing wood ashes with water (lye) was found to have decoloring properties. A similar technique was employed and monopolized by the Dutch who used Lye seasoned with sour milk. The following dates are the milestones leading to what we know as modern bleach.

11th/12th Centuries - Dutch

1600s - Sun-bleaching industry in Western Europe

1774 - Carl Wilhelm Scheele (Paris) - discovered Chlorine

1787 - Claude Louis Berthollet - discovered SH and that it could bleach fabrics

1798 - Charles Tennant - discovered Calcium Hypochlorite - the first bleaching powder

Late 1800s - Louis Pasteur - discovered SH's antibacterial properties

Statue of Karl Vilhelm Scheele by John Börjeson in Humlegården, Stockholm.

Portrait of Comte Claude Louis Berthollet (1749-1822) by N.E. Maurin.

"View of Bleaching Grounds near Haarlem" (1631), oil on panel by Pieter Post, a Dutch Golden Age painter and printmaker.

"Bleaching Ground at Scheveningen" (1882), watercolor painting by Vincent van Gogh, a Dutch Post-Impressionist painter.

Uses and Applications of Bleach

How is Bleach so effective and how does it work? Long story short, Bleach denatures proteins by using itself as a wrecking ball against weak chemical bonds. Sodium Hypochlorite is a strong bully in the chemical world that goes around saying,

"give me an electron or I will come

into close contact with you and take it!!!"

The simplest way to describe bleach is as a "Bond Breaker".

From the chemical bonds of dyes to the cellular membrane bonds of bacteria, Sodium Hypochlorite is not picky and does not care who you are or what your name is. It just wants electrons.

Disinfectant - Sodium Hypochlorite and Bacteria

Why is Sodium Hypochlorite so effective against bacteria and other living organisms? Because SH takes the electrons cells need to live, especially those in the bonds of cellular membranes. Take a look at this video and note how quickly the cellular membrane of microscopic organisms rupture when SH comes into contact with it:

More specifically, SH denatures proteins by taking their electrons and thus breaking their bonds. This short 2-minute video describes this denaturing process in greater detail:


SH not only breaks the bonds of living organisms but of non living compounds as well. A single atom or group of atoms responsible for the color in molecule is called a chromophore.

As it turns out, the hungry-for-an-electron Chlorine in SH bullies the chromophore bonds by taking their electrons as well. This is why bleach (Sodium Hypochlorite) decolors clothes. There are some clothes that bleach does not decolor as they are comprised of synthetic plastic. Nylon, polyester, and acrylic are a few of the fabrics comprised of synthetic materials that won't bleach

Video of food coloring vs Bleach

Whether for Healthcare, the Pool Industry, Hair Products, or Pressure Washing, Sodium Hypochlorite is a household chemical that is not going away anytime soon. Who knew that a chemical bully could be so helpful?


Pool Industry

Hair Products

Pressure Washing

Bleach and Pressure Washing

If you are interested in pressure washing your house or starting a pressure washing business, SH is a handy chemical that can make the job much easier. It is not as helpful at cleaning non-organic dust and dirt, but it excels at cleaning organic dirt such as mildew, mold, and algae which contain cell membranes that when ruptured, cause the death of cells.

To clean siding with green growth on your house, you could follow these steps:

1. Pour 1 gallon of 5% Sodium Hypochlorite (Bleach from the store) and mix it with 1 gallon of water. This will create a 2.5% concentration of bleach.

2. Pour 1/2 cup of Dial Soap in per gallon of Bleach Solution.

- 1/2 cup Dial soap per 1 gallon of solution

- 1 cup Dial soap per 2 gallons of solution.

3. Put this mixture in a handheld spray bottle or backpack sprayer

4. Starting at the bottom, spray a nice coat of solution over the siding.

5. Let the solution sit for 10-15 minutes.

6. Rinse off using a garden hose to provide agitation.

7. If there is still some green on the siding, repeat steps 1-6 until the siding is clean.

Using this home cleaning method can save you time and money in the long run, but there are some warnings that are in order.

Cautions (Personal and Professional)


Sodium Hypochlorite is effective at breaking the cell walls of green growth on residential siding, but it is also effective at breaking the cell walls of the landscaping flowers and grass underneath the siding. What is the answer?

"Dilution is the solution to the pollution."

Sodium Hypochlorite is ineffective when all of its outer shells of electrons are filled. This is why Bleach used in your washing machine can be drained directly into the city plumbing. It doesn't get far in the pipes before it is completely diluted from contact with organic and inorganic matter changing it into other compounds and leaving it completely useless as a chemical.

Before cleaning your siding with SH, water your plants and grass under the wall you will be washing. Not only will this help the plant cells absorb water and be less "thirsty" when the chemical hits them, but it will also help dilute the chemical that will drip off the siding resulting in the concentration of the chemical being much lower when it hits the ground.


SH is a chemical that can damage our body cells. One should only use this chemical with several precautions in place.

  1. Skin - SH can cause burns to the skin, especially at higher concentrations. Avoid all contact with skin by standing upwind while spraying, using proper containers, and wearing full-length clothing to minimize exposure. Also, always wash your hands after coming in contact with this chemical and before touching other body parts.

  2. Lungs - Chlorine (the main chemical in SH) is a lung irritant. It is best to use a respirator when spraying as the aerosols can enter the lungs resulting in mucosal burns and pulmonary edema.

  3. Eyes - I highly recommend wearing glasses when spraying this chemical. It does burn and has the potential to cause damage to the soft tissue of the eyes. If you do happen to get SH in your eyes from splashing, mist, or rubbing your eyes after direct contact, rinse your eyes thoroughly with water for several minutes. This will help dilute and rinse out the chemical to prevent further damage.


To avoid destroying your clothing, which only takes a couple drops, wear clothes that you don't mind destroying, or wear polyester clothes that are SH resistant. Unless of course you are into this look, then by all means, "spray away!"


Before spraying chemicals on any structure, it is important to know what the structure is made of, if there is any paint on it and if so, what kind of pain was used. Most exterior paints are non-carbon meaning SH won't discolor it. However, there are some paints used on doors, siding, and shutters that contain carbon that will be discolored when in contact with SH. Always use caution and verify the kind of paint used on a surface to avoid property damage.


SH is an oxidizing agent meaning it takes the electrons from other materials. SH is an even more potent oxidizer than water which also rusts metal. This means that any metal pressure washing equipment must be thoroughly rinsed and cleaned with regular water to remove the SH and prevent increased corrosion. While I could talk here about the different kinds of pressure washing methods and machines and how to avoid putting SH through your machine, I will have to save that for another post. It is important to winterize all equipment and remove all water from hoses and pumps to prevent rust and gnarly microbes from growing in the standing water.


Bleach (aka Sodium Hypochlorite) is a chemical that gets its potency from being hungry for an electron and not caring what it has to destroy to get it. It is used in many fields including medicine, cleaning, and water sanitation. It can be used for good but its primary active ingredient Chlorine has also been misused as a biological weapon. And finally, it is important to take precautions when using this chemical both for personal and commercial purposes.

And if you are ever curious about which solution to use, always remember,

"Blue Solutions is Your Solution"

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