Potash & Pearl Ash: The Alkaline Origins of American Baking

Front cover and title page scans from Amelia Simmons’s American Cookery (1796)

From Ash to Rise: Potash, Pearl Ash, and the First American Chemical Leaveners

Before commercial baking powder revolutionized the kitchen, early bakers reached for something far more rustic: ashes. Specifically, they utilized the lye-rich remnants of burned hardwood to produce potash and, later, its refined cousin, pearl ash. These alkaline salts, when combined with acidic ingredients, acted as the first chemical leaveners of early American and European baking.

What is Potash?

Potash, or potassium carbonate, is derived from the ashes of burned hardwood. Traditionally, early cooks would soak wood ash in water, extract the resulting lye, and boil off the liquid to concentrate the alkaline residue.  The name "pot ash" originates from the iron pots historically used during this production process. 

Pearl Ash: The Cleaner Leavener

Pearl ash is a purified form of potash.  The refinement process involved dissolving crude potash in water, allowing the insoluble sediment to settle, then filtering and gently evaporating the solution until white crystals formed. This process created a cleaner, more consistent leavening agent preferred for baking cakes and biscuits.

How Alkaline Leavening Works

Neither potash nor pearl ash works alone. They need an acidic partner to trigger a chemical reaction that produces carbon dioxide gas. This gas forms bubbles in batters and doughs, helping them rise and achieve a light texture. 

• Potash: Stronger, more caustic, less refined — best used with caution or in soapmaking.
• Pearl Ash: More purified, milder, and food safe —  suitable for cakes, biscuits, and cookies.

How Does It Compare to Hartshorn?

Hartshorn, or ammonium carbonate, differs in that it does not require an acid to activate.  It's ideal for crisp cookies like Springerle, where dryness is key.  In contrast, potash-based leaveners must be carefully balanced with acidic components, or the resulting bake may carry an unpleasant alkaline flavor.  Potash typically found its place in softer quick breads and early cakes. 

📚 Curious about hartshorn? Click here to explore how bakers used ammonium carbonate before baking soda became common.

Refining Potash into Pearl Ash

Pearl ash isn’t just cleaner potash—it’s the result of a deliberate purification process. Historically, makers dissolved crude potash in water, allowed insoluble impurities to settle out, then filtered and gently evaporated the liquid until white crystals formed. This recrystallized form offered better predictability and reduced off-flavors in baked goods.

Common Acidic Pairings in Historical Recipes

• Buttermilk or clabbered milk
• Molasses (commonly used in gingerbreads)
• Vinegar or sour wine
• Apple cider or citrus juice

Historical Note: Gingerbread with Pearl Ash

The earliest American-published cookbook, American Cookery by Amelia Simmons (1796), includes several recipes calling for pearl ash as a leavening agent. One gingerbread variant reads:

“Gingerbread Cakes” – One quart of molasses, one pound of sugar, three quarters of a pound of shortening, one cup of sour milk, four teaspoons pearl ash, four tablespoons ginger, cinnamon and cloves to taste, and as much flour as will make it roll out.

— Amelia Simmons, American Cookery (1796)

Where to Find Potash or Pearl Ash Today

• Potash: You can make it at home from hardwood ashes, but for safety and consistency, it's best sourced as food-grade potassium carbonate from specialty chemical suppliers or soapmaking shops (e.g., Bulk Apothecary, The Lye Guy).
• Pearl Ash: Much harder to find today, but chemically similar results can be achieved with food-grade potassium carbonate or by using baking soda (sodium bicarbonate) in a modern adaptation.

Example: Gingerbread with Pearl Ash (1796)

Amelia Simmons’s American Cookery (1796) features several gingerbread cookie recipes that call for pearl ash—a purified form of potash—dissolved in milk or water. This marks one of the earliest printed uses of a chemical leavener in American baking. 🧁

View the original 1796 scans, or check the Smithsonian & American Heritage notes on Simmons's innovations :contentReference[oaicite:2]{index=2}.

Historical Example: Gingerbread with Pearl Ash

Adapted from late 18th-century sources:

• 2 cups flour
• 1 cup molasses
• 1/4 cup butter, melted
• 1 tsp pearl ash dissolved in 1 tbsp vinegar
• 1 tsp ginger
• 1/2 tsp cinnamon
• Optional: cloves or nutmeg

1. Mix molasses, butter, and spices.
2. Add pearl ash mixture.
3. Stir in flour gradually to form a dough.
4. Drop by spoonful or roll and cut into rounds.
5. Bake at 350°F for 10–12 minutes.

📜 Want to learn more about potash and pearl ash? Click here to explore how ashes became America’s first chemical leaveners.

The Rise of Baking Powder

The arrival of commercial baking powder made baking more accessible. Unlike potash or pearl ash, it included both alkaline and acidic components, eliminating the guesswork. Home cooks no longer needed to rely on tricky ratios or worry about acidic pairings—baking became easier, faster, and more reliable. This convenience marked the end of Pearl Ash’s reign in the kitchen.

Other Forgotten Leaveners

Before modern yeast and chemical leaveners, a variety of traditional techniques helped baked goods to rise 

• Ale barm: Foam from fermenting beer, used in breads and cakes before commercial yeast.
• Egg leavening: Beaten egg whites or whole eggs incorporated air, helping cakes and sponges rise naturally.
• Sack starters: Fermented mixtures using sack (fortified wine) and flour as makeshift yeast.

Quick Comparison: Forgotten Alkaline Leaveners

Leavener	Source	Needs Acid?	Best Used In
Potash	Boiled wood ash	Yes	Quick breads, early cakes
Pearl Ash	Purified potash	Yes	Gingerbread, sponge cake
Hartshorn	Distilled antlers or hooves	No	Crisp cookies, Springerle

Further Reading & Recipes to Explore

• Hartshorn in Historical Cookies
• Wikipedia: Potash
• Wikipedia: Pearl Ash
• Amelia Simmons’ American Cookery (1796)

🧾 Coming Soon: This post is part of the Forgotten Leaveners series. Watch for the downloadable bundle, including:

• Comparison chart of early leaveners
• Printable recipe cards
• Bonus bakes: potash cakes, Springerle, and more

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