The simplest way to make soda ash at home is to bake ordinary baking soda in your oven. Baking soda (sodium bicarbonate) converts to soda ash (sodium carbonate) when heated, releasing water vapor and carbon dioxide in the process. This takes about an hour at a standard oven temperature and requires no special equipment beyond a baking sheet.
The Baking Soda Method
Spread baking soda in a thin, even layer on a baking sheet or oven-safe dish. Place it in your oven at 400°F (about 200°C) for roughly one hour. The decomposition reaction actually begins at temperatures as low as 200°F (100°C), but a higher temperature ensures complete conversion in a reasonable time. Research on the thermal decomposition of sodium bicarbonate shows the reaction can reach completion in as little as three minutes under ideal lab conditions, but a home oven heats unevenly, so a longer bake gives you a more reliable result.
You’ll know the conversion is complete when the powder looks and feels different. Baking soda is a fine, slightly clumpy powder. Soda ash is grainier, flatter, and more powdery. It also feels almost slippery between your fingers compared to the chalky texture of baking soda. If you want to verify the conversion, dissolve a small amount in water and test it with a pH strip. A 1% solution of soda ash in water has a pH around 11.5, noticeably more alkaline than baking soda, which sits closer to 8.3.
One pound of baking soda yields roughly 0.63 pounds of soda ash, since the reaction drives off water and carbon dioxide. So if you need a specific amount, start with about 60% more baking soda than the soda ash you need.
Why This Works
Heat breaks each molecule of sodium bicarbonate apart. Two molecules of baking soda become one molecule of sodium carbonate (soda ash), plus carbon dioxide gas and water vapor that escape into the air. This is the same final step used in industrial production: even in massive factories, the last stage involves heating sodium bicarbonate to produce the finished soda ash product.
How Soda Ash Is Made Industrially
About 71% of the world’s soda ash comes from synthetic production, with the remaining 29% mined from natural mineral deposits. In 2021, global output was roughly 59 million metric tons, with 42 million tons produced synthetically and 17 million tons from natural sources.
Natural Mining
The United States is the world’s largest natural producer, mining a mineral called trona from massive underground deposits in Wyoming. Trona is a mix of sodium carbonate, sodium bicarbonate, and water. Once mined, it’s crushed, heated to drive off the water and carbon dioxide, then dissolved, filtered, and recrystallized into pure soda ash. The process is straightforward because nature already did most of the chemistry.
The Solvay Process
Most of the world doesn’t have large trona deposits, so factories use the Solvay process, developed in the 1860s. It starts with two cheap, abundant raw materials: salt (sodium chloride) and limestone (calcium carbonate). The core idea is to combine the sodium from salt with the carbonate from limestone, but you can’t just mix them directly. Ammonia acts as a chemical middleman.
Limestone is heated to produce carbon dioxide gas and lime. That carbon dioxide is then bubbled through a tall tower filled with a concentrated salt solution that’s been saturated with ammonia. Inside the tower, a reaction produces sodium bicarbonate, which is less soluble than the other products and crystallizes out of the solution. That sodium bicarbonate is filtered off and heated to produce soda ash, exactly the same heating step you’d do in your kitchen.
The clever part of the Solvay process is its recycling. The lime left over from the limestone is mixed with water and then reacted with the ammonium chloride byproduct to recover the ammonia, which goes right back into the tower. In theory, no ammonia is consumed at all, though small amounts need to be topped off to cover losses.
Common Uses for Homemade Soda Ash
Most people making soda ash at home need it for one of a few specific purposes. Tie-dye and fiber-reactive dyeing is probably the most common. Soda ash raises the pH of the dye bath, which activates the chemical bond between the dye and fabric. Without it, the color washes right out. Soak your fabric in a solution of about one cup of soda ash per gallon of warm water for 15 to 20 minutes before dyeing.
Pool owners use soda ash to raise pH levels. The standard dosage is about 6 ounces per 10,000 gallons of pool water, which raises the pH by roughly 0.2 and total alkalinity by about 5 parts per million. Add it in small increments, letting the water circulate for at least an hour between additions, and retest before adding more.
Soda ash also shows up in soapmaking, glassmaking, and as a water softener. It binds to calcium and magnesium ions in hard water, which is why it’s sometimes called “washing soda.” You’ll find it sold under that name in the laundry aisle, and it’s chemically identical to what you’d make in your oven.
Handling and Storage
Soda ash is not dangerous in the way strong acids or caustic lye are, but it’s alkaline enough to irritate your skin, eyes, and lungs. A 1% solution in water has a pH of 11.5, roughly as alkaline as household ammonia. Wear gloves when working with it, especially in powder form, and avoid breathing the dust. Safety goggles are a good idea if you’re scooping or pouring large amounts. If it gets on your skin, rinse with water. It won’t burn you, but prolonged contact can cause dryness and irritation.
Storage matters more than most people realize. Soda ash is hygroscopic, meaning it actively pulls moisture from the air. At around 72% relative humidity, it starts absorbing water and forms a hydrated crystal. At 84.5% humidity, it absorbs so much water that it essentially dissolves into itself. In practical terms, this means your carefully made soda ash will clump into a solid block if left in a humid environment. Store it in an airtight container, ideally with a desiccant packet, in a cool dry place. Kept sealed, it lasts indefinitely since sodium carbonate is a stable compound that doesn’t degrade over time.