The Complete Guide to Soda Ash (Sodium Carbonate): From Tie-Dye to Pool Chemistry

Soda ash is sodium carbonate (Na₂CO₃), a white, odorless powder with a strongly alkaline pH of about 11.4 in a 1% solution. It is also sold under the names washing soda and sal soda. According to the U.S. Geological Survey, of the soda ash consumed in the U.S. in 2025, glass took 45 percent, followed by chemicals at 28 percent, soap and detergents at 5 percent, flue gas desulfurization at 4 percent, and pulp, paper and water treatment at about 1 percent each. The remaining 16 percent is miscellaneous uses (9 percent) and sales through distributors (7 percent).

If you are looking for a clear explanation of what soda ash does, how to dose it correctly for specific applications, and what grade to buy, this guide covers the subject without unnecessary complexity. Alliance Chemical supplies technical-grade soda ash in bulk for industrial, water-treatment, and craft applications.

What Is Soda Ash?

Soda ash is the industry name for anhydrous sodium carbonate, Na₂CO₃ (CAS 497-19-8), a white alkaline powder that dissolves in water to about pH 11.4. So yes, soda ash and sodium carbonate are the same compound; "soda ash" usually means the dry, water-free form sold in bags for glassmaking, water treatment, pools and dyeing.

What is the chemical formula of soda ash?

The chemical formula of soda ash is Na₂CO₃: two sodium ions (Na⁺) for each carbonate ion (CO₃²⁻), molar mass 105.99 g/mol. It is sometimes typed as "NaCO3", which is wrong; carbonate carries a 2− charge, so it takes two sodium ions to balance it. The crystal form sold as sal soda is the decahydrate, Na₂CO₃·10H₂O (CAS 6132-02-1).

Sodium carbonate is an inorganic salt produced commercially through two primary methods: the Solvay process (synthetic) and trona ore mining (natural). The United States is the world's largest producer of natural soda ash, with major deposits in Wyoming's Green River Basin. Natural soda ash is generally preferred for its lower environmental footprint compared to synthetic production.

Where does soda ash come from? All U.S. soda ash is natural. In 2025, four companies ran five plants on Wyoming trona ore and one company ran a plant on California lake brine, producing about 12 million metric tons, more than half of it exported (USGS Mineral Commodity Summaries 2026). The Green River Basin holds the world's largest known trona deposit. China is the largest producer overall, at about 38 million tons in 2025, most of it synthetic.

Key Chemical Properties

• Chemical formula: Na₂CO₃
• Molecular weight: 105.99 g/mol
• Appearance: white, granular powder
• pH in solution: about 11.4 (1% solution, 11.37 at 25°C)
• Solubility in water: 21.5 g per 100 mL at 20°C
• Melting point: 851°C (1564°F)
• CAS number: 497-19-8

Soda ash is hygroscopic, meaning it absorbs moisture from the air. In humid conditions, it can form lumps or convert partially to sodium carbonate decahydrate (washing soda crystals). Proper sealed storage prevents this.

Soda Ash vs. Washing Soda vs. Baking Soda

Is soda ash the same as baking soda? No. Soda ash is sodium carbonate (Na₂CO₃); baking soda is sodium bicarbonate (NaHCO₃). A 1% soda ash solution is about pH 11.4, while baking soda solution is about pH 8.3, a gap of three pH units, which means more than 1,000 times the hydroxide concentration. Washing soda is sodium carbonate too, usually meaning the crystal decahydrate.

These three names create persistent confusion. Here is the clear distinction:

Is washing soda the same as soda ash? Chemically, yes: both are sodium carbonate. The Merck Index uses "sal soda" and "washing soda" for the decahydrate crystal, Na₂CO₃·10H₂O, which is 63% water by weight, so it takes about 2.7 g of crystals to deliver the sodium carbonate in 1 g of soda ash. Some products sold as washing soda are the anhydrous powder; the formula on the SDS tells you which one you have.

Can I make my own soda ash?

Yes. Heat baking soda (sodium bicarbonate) above 100°C and it turns into soda ash, giving off water and carbon dioxide (2 NaHCO₃ → Na₂CO₃ + H₂O + CO₂). The Merck Index puts the onset at about 50°C and full conversion at 100°C; OECD data give complete decomposition at 270°C. By molar mass, 100 g of baking soda yields about 63 g of soda ash.

Is soda ash the same as borax or OxiClean?

No to both. Borax is sodium tetraborate decahydrate (Na₂B₄O₇·10H₂O), a boron compound with a milder pH of about 9.2. OxiClean Versatile Stain Remover is a mixture: its safety data sheet lists 55 to 70% sodium carbonate (soda ash) and 30 to 40% sodium percarbonate, which splits in water into sodium carbonate and hydrogen peroxide.

What is the pH of sodium carbonate?

Sodium carbonate solutions are strongly alkaline: pH 11.37 at 1%, 11.58 at 5% and 11.70 at 10% by weight, all at 25°C (Kirk-Othmer, via PubChem). The pH climbs only slowly with concentration because carbonate is a weak base, which makes soda ash a controllable alkali for pools and dye baths.

Solubility rises steeply with temperature: about 6.4, 9.3, 20.5 and 39 g per 100 g of water at 0, 10, 20 and 30°C (Kirk-Othmer, converted from 6, 8.5, 17 and 28 wt%), and 30.7 g per 100 g at 25°C (CRC Handbook). Warm water dissolves a tie-dye or pool dose much faster than cold.

How Much Soda Ash for Tie-Dye?

For fiber-reactive dyes (Procion MX and similar), soda ash is the chemical that drives the covalent bond between dye and cellulose fiber. Without it, color washes out within a few launderings. The standard pre-soak is straightforward:

The chemistry: soda ash raises the pH of the pre-soak to roughly 11.5 (1 cup per gallon is about a 6% solution; a 5% solution is pH 11.58 at 25°C), which deprotonates the hydroxyl groups in cellulose and lets the dye molecule chemically bond to the fiber. At lower pH, dyes can only deposit on the surface — they wash out.

• Water temperature: warm (80-100°F) dissolves soda ash faster; cold water works but takes longer
• Soak time: 15-20 minutes is the sweet spot; longer doesn't help and can weaken some fabrics
• Wear gloves: at pH 11.5 prolonged contact dries skin
• Reuse the solution: save and re-use the soak for 2-3 batches before pH starts to drift

How Much Soda Ash to Raise Pool pH?

What does soda ash do to a pool? It raises the pH, and it raises total alkalinity along with it, because it adds carbonate. Baking soda raises total alkalinity with a much smaller pH change, so pool operators use soda ash when pH is low and baking soda when alkalinity is low. To bring pH down instead, see how to lower pool pH with muriatic acid.

Soda ash is the standard chemical for raising pool pH when readings drop below 7.2. It works fast and at much lower doses than sodium bicarbonate would require for the same pH shift.

Other Common Uses for Soda Ash

How do you use soda ash in laundry?

Dissolve about 1/2 cup of soda ash in warm water and add it with your detergent at the start of the wash. It raises the wash-water pH and ties up the calcium and magnesium in hard water as insoluble carbonates, so the detergent works on soil instead of on minerals.

Wear gloves when handling the powder or strong solutions: sodium carbonate is classified as an eye irritant (GHS H319), and alkaline solutions dry skin. Keep it away from aluminum, which alkaline solutions attack.

How Do You Safely Handle Soda Ash?

Soda ash is a mild irritant — far less aggressive than caustic soda (sodium hydroxide) but still warrants basic precautions. The powder is a respiratory and eye irritant; in solution, prolonged skin contact will cause dryness and irritation.

Is soda ash toxic? It is classified as a hazardous chemical, but a mild one: the EU harmonized GHS classification is Warning, H319 (causes serious eye irritation). There is no substance-specific OSHA PEL or NIOSH REL; the dust falls under OSHA's limits for particulates not otherwise regulated, 15 mg/m³ total dust and 5 mg/m³ respirable fraction (29 CFR 1910.1000, Table Z-1). Read the SDS before handling.

• Gloves: nitrile or rubber for handling solutions; cotton/leather for handling dry powder
• Eye protection: safety glasses for pouring or scooping
• Respiratory: avoid creating dust; use an N95 if scooping bulk quantities
• Spills: sweep up dry powder; mop up solution with plenty of water
• Storage: sealed container in a dry location; indefinite shelf life
• Disposal: dilute solutions can usually be drain-disposed (check local regs); large quantities require hazardous-waste handling

What Grade of Soda Ash Should You Buy?

Most applications need only technical grade (95-99% pure Na₂CO₃). Higher purity grades exist (USP, reagent) but are unnecessary outside of pharma or precision analytical work.

Alliance Chemical supplies natural-source technical-grade soda ash in 2 lb and 5 lb packs and 50 lb bags, up to 40-bag (2,000 lb) lots. Need the Certificate of Analysis? Just ask, we send it at no charge.