Caustic Soda vs Soda Ash: A Base-ic Comparison

Soda Ash, Sodium Carbonate vs Caustic Soda, Sodium HydroxideCaustic Soda (also known as Sodium Hydroxide) and Soda Ash (also known as Sodium Carbonate) are both bases. This means they have a high pH. They may be a useful source of alkalinity in a wide variety of industrial applications such as pulp and paper, water treatment, detergent and soap production, and pH adjustment.

If you are using Caustic Soda in your manufacturing process, you may have noticed that, for various reasons, the price of this chemical has been increasing steadily over the past couple of years. You may have wondered if there is a more cost-effective source of alkalinity, such as natural Soda Ash. Here is a base-ic comparison (pun intended!) of these two chemicals: Soda Ash and Caustic Soda.

Caustic Soda (Sodium Hydroxide)

Caustic Soda 50% Solution has a pH of 14 and is one of the strongest bases. It is highly corrosive and hazardous and generates heat when diluting. It comes in dry and liquid form and may be purchased pre-mixed in many various dilutions. Due to the hazards, it is regulated by DOT for shipping. Sodium Hydroxide is produced via the Chlor-Alkali process along with Chlorine and Hydrogen gas. Price and supply are closely tied to Chlorine demand, which is volatile and can fluctuate a lot due to world events and economic changes.

Soda Ash (Sodium Carbonate)

Soda Ash has a pH of around 11.6. As a base, it is not as strong as Caustic Soda. This means that slightly more product will be needed to do the same job (approximately 10 lbs of Caustic Soda does the work of 13 lbs of Soda Ash). It is a much less caustic source of alkalinity. As such, it is non-hazardous, does not incur hazmat fees when shipping, and is not regulated. It is typically sold and shipped in dry form, saving the cost of shipping water. (However, this may mean that an extra step is created in the production process of putting the product into a solution for use. Also, it may leave residue at the bottom of the container.) It is more eco-friendly and biodegradable, and does not generate heat when mixing. Safety and environmental considerations help make Soda Ash an attractive alternative.

Since Soda Ash is mined from the mineral Trona and derived from natural sources, it typically has much greater price stability than Caustic Soda. Supply of the chemical is stable as well.


If you’re thinking of switching from Caustic Soda to Soda Ash, consider whether or not structural changes would have to be made to accommodate the change. Caustic Soda and Soda Ash in solution may be able to use the same equipment (a standard chemical feed pump drawing from a tank of solution). However, a switch from liquid Caustic to dry Soda Ash (such as in detergent making) may mean making changes to a production facility that could cause additional expense. Regardless, the team at CORECHEM is happy to help. Get in touch with a representative to discuss your source of alkalinity and any changes you may be considering.