When WD-40 launched in 1953, the formula was the 40th attempt to create a water displacement spray for the Atlas missile program — the chemists never patented it because filing would have required disclosing the recipe, and the unpatented formula has remained a trade secret for 73 years

In 1953, a small lab in San Diego called Rocket Chemical Company was trying to solve a mundane but expensive problem for Convair, the aerospace contractor building the Atlas intercontinental ballistic missile. The missile’s thin steel skin kept rusting. Water seeped into seams. Corrosion threatened the airframe of America’s first nuclear deterrent. A three-person team led by chemist Norm Larsen mixed batch after batch of a water-displacing solvent, numbering each attempt as they went. The 40th try worked. They called it WD-40 — Water Displacement, 40th formula — and quietly handed it to Convair to wipe down missile parts.

Seventy-three years later, that exact formula still sells in the blue-and-yellow can, and no one outside a tiny circle at WD-40 Company knows what is in it.

That is not an accident. It is the most consequential business decision Larsen never made: he refused to file a patent.

The choice that built a 73-year moat

A patent would have given Rocket Chemical exclusive rights for a limited period — at the cost of publishing the recipe in full for the world to read. After expiration, any chemist could have copied it legally. Larsen did the math the other way. Keep the formula locked in a safe, manufacture the concentrate in a single facility, and the protection lasts as long as the secret holds.

The legal logic behind that choice is the same logic Coca-Cola and KFC used. As a recent analysis in The Legal Intelligencer puts it, trade secrets offer significant value through their potentially indefinite duration and the competitive advantage they provide, according to legal analysis. A patent is a time-limited monopoly. A trade secret can run forever — if you can keep it quiet.

Larsen could. The Atlas program was classified. The product was industrial. There was no consumer pressure to publish technical specs. So he didn’t.

From missile skins to kitchen drawers

In 1958, a Rocket Chemical employee snuck a can home and used it on a squeaky door. Others followed. Larsen noticed and put WD-40 in aerosol cans for retail sale in San Diego hardware stores in 1958. By 1969, the company had renamed itself after its only product. By the early 1990s, WD-40 had achieved extraordinary market penetration in American households. Today the company reports the product is sold in more than 176 countries.

None of that distribution would have been possible if a competitor could legally reverse-engineer the formula and undercut on price. And reverse-engineering is genuinely hard here — gas chromatography can identify components, but ratios, manufacturing sequence, and the specific petroleum distillate base are difficult to replicate at scale. The Material Safety Data Sheet lists ingredient categories, not proportions. The full recipe sits in a bank vault. In 2018, the company’s CEO told reporters the formula had been moved to a vault in San Diego for a publicity ceremony — the kind of theater that, as a marketing move, doubles as legal reinforcement of the secret’s value.

Why patents would have killed it

The brutal lesson about patent disclosure showed up in a 2025 Federal Circuit ruling. As JD Supra reported, courts have held that information disclosed in a patent filing loses trade secret protection and cannot be reclaimed as confidential later. Ever.

That principle is what makes the patent-versus-trade-secret choice a one-way door. File the patent, and you trade duration for enforcement power. Keep the secret, and you trade enforcement power for duration — potentially forever, but only if you maintain what trade secret protection requires maintaining adequate security measures, a standard known in legal contexts as reasonable measures.

WD-40 Company maintains those measures with almost theatrical discipline. Only a handful of employees know the formula. The concentrate is mixed at a single facility and shipped to bottlers worldwide already blended, so the people filling the cans don’t know what they are filling them with. NDAs, restricted access, and physical security all stack up. A 2026 analysis of trade secret litigation in JD Supra notes that establishing trade secret status requires demonstrable, ongoing efforts to maintain secrecy — not just an intent to keep things quiet.

The story is the product

Here is where the formula itself becomes almost beside the point. WD-40 works. So do dozens of competing penetrating lubricants. Liquid Wrench, PB Blaster, 3-IN-ONE, Kroil — chemists at any of those companies could formulate something that performs nearly identically. Some perform better on specific tasks. None of them have a 73-year-old origin story attached to a Cold War missile program.

And that story, as much as the chemistry, is what consumers buy. Research published in Psychology Today by consumer psychologist Peter Noel Murray has noted that purchasing decisions are often driven more by emotional brand connections and self-identification than by rational analysis. The narrative is the emotional connection. The emotional connection is the loyalty.

WD-40’s narrative is unbeatable. A scrappy three-person team. Forty attempts. A missile program. A formula so good it never needed to change. A secret in a vault. That is a story a hardware store customer can repeat to a friend in 30 seconds, and it does more brand work than any ad campaign. The same logic explains why founder-origin myths drive so much consumer behavior — Phil Knight’s trunk-of-the-Plymouth Nike story still anchors a massive global brand six decades later.

What founders keep getting wrong about IP

Most early-stage founders default to patenting everything they can. It feels sophisticated. It signals seriousness to investors. It produces a tangible asset on the balance sheet. But patents are public, finite, and expensive to enforce. The right question is rarely about how to patent something — instead, founders should ask what kind of protection actually fits how the product will be sold and how easily it can be copied.

A consumer product with a manufacturing process competitors cannot easily reverse-engineer is often better served as a trade secret. Software algorithms running on a private server are often better as trade secrets. Recipes, formulas, proprietary chemical processes — almost always trade secrets. A new mechanical device that ships to customers and can be taken apart on a workbench? That needs a patent, because the secret is already out the moment the first unit sells.

A recent IPWatchdog analysis of Federal Circuit rulings shows courts are still actively redrawing the lines between patent and trade secret enforcement, which means founders who treat the choice as a one-time legal checkbox are exposing themselves to risks they haven’t priced. The choice is strategic, not administrative.

The 73-year compound interest of one decision

WD-40 Company has built a remarkable business on a single core product line. The company has paid dividends to shareholders consistently for decades. Its gross margins consistently run well above typical commodity chemical products. That margin exists because no generic version of WD-40 exists. There is no expired patent for a competitor to copy. There is only the can, the smell, the story, and the lock on the vault.

Larsen sold his stake in 1969 for what was reportedly a modest sum. He died in 1970. He never saw what his refusal to file paperwork would become — a single decision in 1953 that compounded for seven decades because it removed an expiration date from a competitive advantage.

The Atlas missile was decommissioned in the 1960s. The corrosion problem it was built to solve is now solved by other coatings on other airframes. The chemistry Larsen perfected has been technically surpassed by newer lubricants in nearly every measurable category. None of it matters. The can is still on the shelf, the formula is still in the vault, and somewhere in San Diego a small group of people who signed NDAs know exactly what is inside — and have no reason, legal or commercial, to ever say.