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What is the Difference Between Washing Soda and Soda Ash?

Washing soda and soda ash are both forms of sodium carbonate, but they differ in water content and purity. Washing soda, with added water molecules, is a household cleaner, while soda ash, purer and more concentrated, is used industrially. Intrigued by how these subtle differences impact their uses? Discover the myriad ways each compound plays a role in our daily lives.
Mandi Rogier
Mandi Rogier

Washing soda and soda ash are two different names for the same substance. Both are terms used to refer to sodium carbonate, or Na2CO3. Other names for this substance include soda crystals and sal soda.

Sodium carbonate occurs naturally in the ashes of many plants. It is often found in the mineral deposits left behind from seasonal lakes. Seaweed ashes are one of the most common sources of natural sodium carbonate. It is likely from this association that it earned the moniker “soda ash.”

Soda ash.
Soda ash.

In addition to its natural form, soda ash can also be created through chemical processes. The Solvay process is the most prevalent. In this process, the heating of calcium carbonate combined with sodium chloride and ammonia produces sodium bicarbonate, which can in turn be heated to produce sodium carbonate.

Hou’s process is another way to create soda ash or washing soda. This process is very similar to the Solvay process. The final steps differ in that ammonia, carbon dioxide, and salt are added to the ammonium chloride solution. When cooled, this combination generates sodium carbonate.

Washing soda may be used to supplement detergent.
Washing soda may be used to supplement detergent.

Washing soda or soda ash appears as a fine white powder, which dissolves in water. It can be purchased commercially and used for common household purposes. Sodium carbonate is also used in many industrial processes. This substance acts as an alkaline agent for chemical and industrial uses. It is used in glass making and paper production. It can even be used in cooking in lieu of sodium hydroxide. Sodium carbonate is even used to make Ramen noodle flavoring.

The term washing soda has been applied to sodium carbonate due to its myriad purposes as a household cleaning agent. It is present in many washing detergents and can be used on its own for a variety of cleaning jobs. As a basic, multi-purpose cleaner, it can be used on nearly any surface with the exclusion of aluminum and fiberglass, which can be scratched by washing soda.

To experience the full range of washing soda’s usefulness, try adding it to a load of wash to supplement your detergent. Difficult stains from oil, grease, coffee, tea, ink, and blood can often be removed from clothing and other fabrics with this substance. Attack grease stains on pots and pans or kitchen surfaces with washing soda as well.

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Discussion Comments


Some forms of soda ash (e.g. that labeled as 'washing soda') contain more water molecules than others, which makes them weigh more and be larger for a given number of sodium carbonate molecules - this means that you need to measure out a larger quantity of the hydrated form in order to get the same results. If you buy sodium carbonate without the extra water molecules, then store it for several years in humid conditions, it will absorb some water and appear to lose strength, when in fact it has merely 'bulked up' and needs to be used in larger volumes.

The type of sodium carbonate used in washing soda is a decahydrate, so you need to use a lot more washing soda than you would anhydrous soda ash, perhaps three times as much - assuming that you are able to find pure unadulterated washing soda that is suitable for [your purpose]. (In theory, we should use 2.7 times as much washing soda as a substitute for soda ash, if measuring by weight, or 4.6 times as much if measuring by volume.)


The article mentioned the Solvay process used to create soda ash from table salt or plant ashes. While it may be possible to extract sodium carbonate from salt, coal ash, and other industrial sources, these techniques are less economical.

There are many naturally occurring sources of sodium carbonate that can be refined through the Solvay process, or elements of the Solvay process, to extract sodium carbonate. Using naturally occurring sources is cheaper than separating sodium carbonate from other manufactured sources (salt), or from toxic and radioactive materials (coal ash).

Soda carbonate containing minerals that miners dredge from alkaline lakes are very easy to extract, and the source is renewable.


@ GlassAxe- Soda-lime glass accounts for the majority of glass produced. Sodium carbonate is used in glass production to lower the melting point of silica, making the production process less energy intensive.

Sodium carbonate does have a flaw in glass production. Sodium carbonate makes glass water soluble, causing it to deteriorate slowly in water.

This brings me to why it the industry calls some glass soda-lime glass. To overcome the water solubility of pure sodium carbonate glass, manufacturers add calcium oxide from limestone.

Manufacturers also add other chemicals to change further the properties of soda-lime glass.

Pyrex and heat resistant glass has added boron, lanthanum oxide is used to make glass for lenses, iron is used in the glass for movie projector lenses, and cerium oxide is used for those expensive sunglasses that block UVA and UVB rays.


As the article stated, Soda ash has many industrial uses. Industry uses soda ash in the production of glass for automobiles and commercial buildings, Petroleum refining, and water treatment. Soda ash is also the main ingredient in powdered laundry detergent.

Because of these industrial uses soda ash mining is more than a half billion dollar a year industry in the United States. This may not seem like much, but sodium bicarbonate counts for about two or three percent of all non-fuel mining resources. Sodium carbonate is one of the top chemicals produced in this country.

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    • Washing soda may be used to supplement detergent.
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      Washing soda may be used to supplement detergent.