Potash: The Chemical Behind America’s First Patent — and What It Became

On July 31, 1790, George Washington signed the first patent the United States ever issued. It was not for a loom, an engine, or a gun. It was for a better way to boil wood ashes. The document ran a few hundred words, carried the signatures of the President, the Secretary of State and the Attorney General, and granted one Philadelphia manufacturer exclusive rights to an improved method of making pot ash and pearl ash. Patent number one, in the country that would go on to issue twelve million of them, was a chemistry patent — and the chemical it covered is still on our shelves, in a form the man who patented it would not recognize.

What is potash?

Potash is the collective name for a group of water-soluble salts that carry the element potassium, and historically it meant one compound in particular: potassium carbonate, K₂CO₃, leached out of wood ash with water and boiled down to a white residue in an iron pot.

That is not a folk etymology — it is the literal one. The word entered English around 1477 from the Middle Dutch potaschen, “pot ashes,” describing exactly what the process produced: ash, in a pot. When Humphry Davy pulled a new silvery metal out of this material in 1807, he named the element after the substance it came from. Potassium is named after potash, not the other way round. The element’s symbol, K, comes from a second route entirely — kalium, from the Arabic al-qalyah, “plant ashes,” which also gives us the word alkali.

So the name of one of the most important elements in biology, the symbol on every blood-panel printout, and the entire English word “alkali” all trace back to the same humble industrial act: burning plants and washing the ashes.

Why was America’s first patent for potash?

Because in 1790 potash was America’s most valuable manufactured chemical export, and the young republic had an enormous amount of the raw material lying around: forest.

Every acre a settler cleared produced tons of wood that had no market and had to be burned anyway. Leaching those ashes turned a waste product of land-clearing into a dense, non-perishable, shippable commodity that Britain’s textile and glass industries would buy in quantity. Potash bleached linen, fluxed glass, and saponified fat into soap. For a farm family on the frontier, the ash barrel was often the only thing on the property that generated hard currency.

The Patent Act was signed in April 1790. Within four months, the first grant went to Samuel Hopkins for “an Improvement, not known or used before, in the making of Pot ash and Pearl ash by a new Apparatus and Process.” The signatures on it were George Washington, Thomas Jefferson as Secretary of State, and Attorney General Edmund Randolph — the entire patent examining board of the United States at the time consisted of those three men, reviewing applications personally.

Hopkins’s actual innovation was procedural, and the patent spells it out in four numbered steps: burn the raw ashes in a furnace, dissolve and boil them in water, draw off and settle the ley, then boil the ley down to salts. The novelty is named explicitly in the document — the operation of “burning the raw Ashes in a Furnace, preparatory to their Dissolution and boiling in Water, is new, leaves little Residuum; and produces a much greater Quantity of Salt.”

In modern terms he was oxidizing the unburned carbon still left in the ash and carbonating more of the potassium before leaching, which is why his yield went up. It is exactly the kind of unglamorous process improvement that most industrial chemistry still consists of — not a new substance, just more of it out of the same barrel of ash.

The story has one more twist. In 1836 a fire destroyed the Patent Office and most of the records of the first forty-six years of American invention. Roughly 10,000 patents burned. The surviving pre-1836 grants were later renumbered with an X prefix, which is why the first United States patent is formally X1. Hopkins’s original parchment survived the fire only because it was not in the building — it was in private hands, and eventually reached the Chicago History Museum, where it remains.

Is potash just wood ash?

No — wood ash is the raw material, and potash is what you get after washing the soluble fraction out of it and evaporating the water away. The distinction is the entire industry.

Wood ash is a mixture: mostly calcium compounds, silica, unburned carbon, trace metals, and a minority fraction of soluble potassium salts. Pour water through it and the potassium carbonate dissolves while most of the rest does not. Boil that solution down and the white solid left behind is potash. Re-fire that solid and you have pearl ash. Each step throws away mass and buys purity — which is the same trade every chemical grade in our catalog represents, four hundred years later.

It is worth being blunt about the home-made version, because the search results for this are full of enthusiasm and short on hazard. Ash leachate is a genuinely caustic alkaline solution of uncontrolled and unknowable concentration, contaminated with whatever was in the wood and the fire. It will burn skin and destroy eyes exactly as well as a laboratory reagent will, with none of the labeling that would tell an emergency room what it was. If you need a defined alkali, buy a defined alkali with a certificate of analysis attached to it.

What is caustic potash?

Caustic potash is potassium hydroxide (KOH) — a far stronger base than the potassium carbonate of traditional potash, and the member of the potash family that industry actually runs on today.

Historically it was made by treating a potash solution with slaked lime, which swapped the carbonate away and left hydroxide behind — a reaction called causticization, and the origin of the word “caustic” in both caustic potash and caustic soda. Modern KOH is made electrolytically from potassium chloride brine, the same basic industrial route that produces sodium hydroxide from salt.

This is the compound Humphry Davy chose in 1807 when he wanted to know what was hiding inside these ancient alkalis. He melted caustic potash and ran a current through it, and metallic potassium appeared at the negative electrode — violently, since it reacts with the moisture in air. It was the first metal ever isolated by electrolysis, and it made Davy the first person to see an element that had been used industrially for three thousand years without anyone knowing it was there.

What is potash used for today?

About 85% of U.S. potash sales go to the fertilizer industry, and the remainder goes to chemical and industrial applications — and those two halves of the market are so different that they barely share a supply chain.

The agricultural half is potassium chloride, mined as ore in New Mexico, Utah and above all Saskatchewan, spread on fields by the millions of tons to replace the potassium that crops remove from soil. That is the potash of commodity price charts and trade policy. It is not what a chemical distributor sells.

The industrial half is where caustic potash lives:

• Liquid and soft soaps. Potassium soaps are soft or liquid where sodium soaps are hard bars — the difference is literally which alkali saponified the fat. Traditional liquid castile soap is a KOH product. See our companion piece on sodium hydroxide in soapmaking for the other half of that chemistry.
• Biodiesel. KOH is a common transesterification catalyst, favored over NaOH in some processes because the resulting potassium-bearing glycerol byproduct is easier to handle.
• Alkaline batteries. The electrolyte in a standard alkaline cell is potassium hydroxide solution. The battery category is named after the chemical inside it.
• Alkaline electrolysis. KOH solution is the classic electrolyte for splitting water into hydrogen and oxygen — covered in depth in our article on KOH in electrolysis.
• pH control and neutralization in process water, plating baths and wastewater streams, where the potassium ion is preferred to sodium.
• Potassium salt manufacture — KOH is the feedstock route to potassium carbonate, potassium citrate, potassium silicate and the rest of the potassium chemicals family.

Potash, caustic potash, or lye: which one do you actually need?

Start with what the material has to do, because the three are not substitutes and the word “potash” on its own does not identify a product.

To be direct about what we stock: Alliance Chemical is an industrial chemical distributor, not an agricultural one. We supply caustic potash — potassium hydroxide — and we do not sell potassium chloride fertilizer. If you arrived here looking for potash to spread on a field, a fertilizer dealer is the right supplier and we would rather say so than sell you a drum of strong base.

Can the U.S. supply its own potash?

Not at anything close to current consumption. The United States imported about 5.6 million tons of potash in 2025 against roughly 500,000 tons of domestic production, leaving net import reliance at 92% of apparent consumption.

The reason is geological rather than industrial. Economic potash deposits are the evaporite remains of ancient seas, and the largest and richest of them in North America sits under Saskatchewan. U.S. production comes mainly from southeastern New Mexico and from Utah brines — real, but small against a market that consumes roughly 5.9 million tons a year.

This is worth understanding even if you only ever buy the industrial grades, because it explains the price behavior. Potash pricing is set by a globally traded, geographically concentrated, policy-exposed commodity market. When fertilizer potash moves on tariffs or sanctions, the raw material feeding the chemical branch of the family moves with it.

Should you buy potassium hydroxide as flakes or as a liquid solution?

Buy flakes when you need concentration and long storage and can safely handle a solid dissolution step; buy a solution when you want a ready-to-dose liquid and would rather not run that step at all.

The dissolution step is the real decision. Dropping KOH flakes into water is strongly exothermic — the solution heats itself, sometimes dramatically, and adding water to concentrated caustic rather than caustic to water is a classic way to make it boil and spit. Doing that safely at scale needs cooling, agitation, the right vessel and trained hands. A pre-made solution has already had that done under controlled conditions.

The 2026 addition to our line is the liquid side of that table: caustic potash pre-mixed at 25%, 30% and 45%, from single quarts up to 15-gallon drums and pallet quantities. It exists because a meaningful share of the people buying flakes were dissolving them to a fixed strength anyway, and paying for the privilege in labor, cooling and risk.

How dangerous is caustic potash, and how should it be handled?

Potassium hydroxide is corrosive to skin, eyes and the respiratory tract, and eye contact can cause permanent injury very quickly — it is handled with the same seriousness as any strong caustic, not with the casualness the word “wood ash” invites.

• Personal protection: chemical splash goggles (not safety glasses alone), a face shield when pouring or transferring, gloves rated for caustics, and a chemical apron.
• Dissolving: always add caustic to water, never water to caustic, slowly, with agitation and cooling. Never dissolve in a closed or glass-thin vessel.
• Never mix with acids without deliberate neutralization design — the reaction is violently exothermic. Contact with aluminum, zinc, tin and galvanized surfaces generates hydrogen gas.
• Storage: keep flakes sealed and dry; KOH pulls moisture from the air. Store liquids in compatible containers, away from acids and incompatible metals.
• Exposure limits: NIOSH sets a ceiling recommended exposure limit of 2 mg/m³ for potassium hydroxide.
• First aid: flush exposed skin or eyes with running water for at least 15–20 minutes and get medical attention. Have the SDS in hand when you call.

Key numbers and sources

Related reading

• Potassium hydroxide: uses, grades and safety — the working reference for KOH itself, grade by grade.
• How to buy potassium hydroxide — pack sizes, documentation, freight and what to ask a supplier.
• KOH in electrolysis and hydrogen production — why alkaline electrolyzers run on caustic potash.
• Caustic soda guide — the sodium half of the caustic story, and when to choose it instead.
• Who discovered phosphorus? — Hennig Brand, 1669, and the birth of phosphoric acid.
• Who discovered ammonia? — sal ammoniac, the salt of Ammon, and a very old supply chain.
• Ignaz Semmelweis and chlorinated lime — the chemistry that proved handwashing worked.