Hoppe's No. 9: How a 1903 Solvent Became Gun-Cleaning Legend

A smell with a birth certificate

Very few smells can be dated. The smell of a Hoppe's No. 9 bottle can: 1903, Philadelphia.

For generations of shooters, that odour is the smell of a kitchen table covered in newspaper, a cleaning rod, a box of patches and a parent explaining how to push from the chamber end. GUNS Magazine writer Dave Workman called it one of his "sensual memories," and the company eventually put the scent into an air freshener because people asked for it.

But No. 9 did not start as nostalgia. It started as an answer to a corrosion problem in a brand-new Army rifle, worked out by a man who had spent most of his life mixing paint.

The paint man in the National Guard

Frank August Hoppe was born in Philadelphia on May 15, 1869, to German immigrant parents, according to a detailed profile published by USCCA. He went to work young, joining paint and varnish maker William Waterall in 1882, and later ran the paint department at Achenbach & Miller for about two decades.

That background matters. The paint and varnish trade was, at heart, applied chemistry: solvents, oils, carriers, how mixtures behave on metal. American Rifleman describes Hoppe as bringing two decades of paint industry knowledge to his solvent.

His other life was military. Hoppe joined the Pennsylvania National Guard in June 1887 and, over three decades, rose from private to captain. During the Spanish-American War, the USCCA profile says, his company was stationed at Montchanin, Delaware, guarding the DuPont smokeless powder works. He was also a competitive shooter, and the same profile records him as a team captain in state competitions in 1908.

So here was a man who knew solvents, knew rifles and knew from first-hand experience what it was like to make a company of soldiers clean them.

The problem in the barrel

At the turn of the century, the U.S. Army was fielding a new service rifle, the Springfield M1903, chambered for a cartridge known as the .30-'03. American Rifleman notes that the early smokeless powder used with it proved more corrosive than expected. Barrels fouled and eroded, and cleaning was a long, unpleasant chore.

The USCCA profile describes the cleaning method the Ordnance Department had been recommending as a slow and laborious mixture involving ammonium compounds and water. It worked, but it was not something a tired soldier looked forward to.

In 1903, Hoppe combined nine chemicals into a solvent that, as he and later his company described it, removed powder residue and metal and lead fouling and protected the bore against rust. According to American Rifleman, it cut the time his troops spent cleaning their rifles.

Timing helped. The .30-'06 cartridge arrived in 1906 and reduced the bore erosion problem. But in the three years in between, American Rifleman says, Hoppe's solution "gained momentum."

Naming the number

On July 3, 1907, Hoppe registered a trademark for a "liquid chemical composition" called Nitro Power Solvent No. 9. The name has been explained ever since as a nod to the nine chemicals in the original mix. Over time, the official name faded and the shorthand took over: Hoppe's No. 9, or simply "Hoppe's."

Early marketing was ambitious. The company claimed "one thousand and one uses," the USCCA profile notes, listing tools, cutlery, machinery, automotive parts and even typewriters. Olympic gold medallist and marksman Charles B. Winder was quoted praising it. It was a small product with a big pitch.

The founder's short life

Frank Hoppe did not get to see what his solvent became. He died on January 16, 1921, after a stroke, at age 51. His son, Frank Chestin Hoppe, became company president.

The business that followed outgrew its founder's original bottle many times over. American Rifleman describes how the brand expanded from solvents into oils, tools and other cleaning supplies, including the BoreSnake, the GunMedic line and many all-in-one cleaning kits. The company is no longer family-owned. By 2023, Hoppe's was billing itself as the industry's oldest gun-cleaning-supply brand and celebrating 120 years.

How a cleaner became a scent

Plenty of products last a century. Few become a smell people want in their truck.

In 2010, Field & Stream reported that Hoppe's had released a No. 9 air freshener, describing it as a response to consumer requests and calling No. 9 "the most recognizable scent in the outdoors." It was not a joke product, though it was greeted with a few jokes. Workman's 2024 GUNS Magazine column joked that it should be sold as aftershave, and noted the scent turning up in holsters, cases, cleaning cloths and an old rifle cover.

Why the smell sticks in memory is partly simple exposure. No. 9 is used at the moments people remember: a first gun, a hunting season, a lesson from a parent or grandparent. A strong, distinctive odour tied to those moments is hard to forget.

What a bore solvent actually does

It helps to know what Frank Hoppe was solving, because it explains why "No. 9" became shorthand for cleaning itself.

Every shot leaves something behind in the barrel. Burnt powder residue, often called carbon fouling, coats the bore. Bullets that touch the rifling can leave thin traces of copper or lead. Left alone, those deposits can build up, trap moisture and contribute to rust. A bore solvent is a chemical designed to loosen or dissolve those deposits so patches and brushes can carry them out.

That is a different job from a lubricant, which reduces friction on moving parts, or a protectant, which leaves a film to slow rust. Many modern products combine cleaning, lubricating and protecting in one bottle, usually sold as CLP. Hoppe's itself now sells oils, tools and other supplies alongside the original solvent.

So the old No. 9 bottle is best understood as the first step in a routine, not the whole routine. Clean the bore with solvent, dry it, then protect it with a light oil if the gun is going into storage.

A century of brand stretch

What began as one bottle has become a family of cleaning products. American Rifleman's anniversary piece names the BoreSnake (a one-pass pull-through bore cleaner), the GunMedic line and a range of all-in-one kits among the brand's well-known products. Earlier, the company's own marketing pushed No. 9 well beyond guns, claiming uses on tools, cutlery and machinery.

There's a pattern there. The brand has always sold convenience along with chemistry: something that cuts the time between the range and putting the gun away. That was the original promise to Hoppe's Guard troops, and it is still the pitch for a pull-through bore cleaner today.

Myth vs fact

"The number is because it was his ninth attempt." The commonly cited explanation, repeated in the histories used here, is nine chemicals, not nine tries.

"It was invented for the Army." Not exactly. Hoppe was a Guard officer who made it to help his own troops. It became popular with soldiers and shooters, but the sources here don't describe it as an Army contract product.

"It's the same bottle as 1903." The brand has offered many products since, and formulations and packaging change over time. Check the current label for what is in the bottle you buy.

Using it today

The classic No. 9 is a bore solvent. A typical routine is to wet a patch or bore brush, run it through the bore from the chamber end where possible, let it work, then follow with dry patches and a light coat of oil. Our cleaning solvents and oils guide covers how solvents and lubricants divide the job.

If you want the smell without the cleaning, the air freshener still exists. If you want the cleaning without the smell, many modern low-odour solvents are available, and they may suit an apartment better.

Before you clean, unload the firearm, remove the magazine, check the chamber twice and keep ammunition out of the cleaning area. Then open the bottle. You'll know the smell.

Editorial note: This is an independent editorial overview built from manufacturer specifications, retailer listings and published sources. We have not performed hands-on testing of the products discussed, and nothing here is a performance guarantee. Verify specifications, compatibility and the law where you live.

Affiliate disclosure: Some links on this page are affiliate links to Amazon. We may earn a commission if you buy through them, at no extra cost to you. Our editorial choices are not influenced by commissions. Check current price, stock and specifications directly with the retailer.