fire pit

It transformed the fate of nations; it changed the way wars were fought, made weak countries strong and strong kingdoms weak. It ended the Middle Ages and ushered in the Renaissance with a bang. Its gush of hot, expanding gas blew away feudalism, for no longer could chain-mailed knights on horseback, invulnerable to hand-held weapons and arrows, maintain domination over their fiefdoms. In my estimation, black powder, or gunpowder, is the most important chemical discovery in the history of mankind.

For a thousand years, black powder was the only propellant and explosive in existence, making it the most powerful, deadly, entertaining, and politically potent chemical on Earth.

Because gunpowder was cheap and relatively simple to make compared to fashioning armor, it was the great equalizer among those who fought. It led to the supremacy of technology over arm strength, making engineers and scientists more important than knights and ninjas.

Francis Bacon, the English statesman, essayist, and philosopher, wrote that gunpowder (along with printing and the magnetic compass) had “changed the whole face and state of things throughout the world … insomuch that no empire, no sect, no star seems to have exerted greater power and influence in human affairs.”

Despite its essential simplicity, compounding black powder is not for everybody. While relatively tame compared to its high-energy cousins, flash powder and smokeless powder, black powder has more than enough brisance to blow off valuable body parts if handled carelessly. But after reading several books dealing with the subject, I decided that I couldn’t intimately understand the stuff until

I made it myself. Making black powder is intellectually stimulating and historically revealing, and it gave me a degree of insight into this important discovery that simply reading about it never could. The first time I smelled the smoke and saw the fire issuing from the magic powder I’d compounded, I knew immediately that this was something special.

I’ll remember that bang for the rest of my life.

The Fire Drug

The Chinese invented gunpowder, which they called “the fire drug” or “magic black powder.” The exact dates are uncertain, but by the 10th century, gunpowder was in use for ceremonial and entertainment purposes, if not in warfare.

Gunpowder is composed of three ingredients: potassium nitrate (often called saltpeter), sulfur, and charcoal. In parts of China, gunpowder makers could merely scoop up saltpeter lying on the ground, the result of the fermentation of soil and animal waste in the humid subtropical climate.

Europeans living in a dryer, colder environment had to work harder to get their saltpeter. The early European method of obtaining potassium nitrate involved aggregating great heaps of rotting organic matter, especially that which contained high percentages of rotted meat and animal dung. “Petermen” would search out promising places to collect their smelly treasure (abandoned outhouses and animal pens being especially prized). The petermen would taste the earth, and when they found a place that tasted right, they’d cart out the soil, boil it in vats, then evaporate and strain the residue. The result was high-purity saltpeter.

But once you have the ingredients, you can’t just shake them up in a jar. The ratio and the manner in which they must be combined are precise and unforgiving. Mixed in the right way, the chemicals become the magic black powder. Combined incorrectly, they’re a mound of unimpressive black dust.

How It Works

Each ingredient has a specific job to do in producing the desired chemical reaction. The charcoal is the fuel. Made correctly, it is virtually pure carbon. Unlike other forms of pure carbon such as coal or diamond, charcoal’s lattice-like structure is filled with microscopic pits and voids that are critical for rapid burning.

The saltpeter is what chemists call an oxidizer. It willingly gives up the oxygen locked within its chemical structure to a nearby fuel, allowing for burning. Of course, charcoal burns with ordinary oxygen available in the surrounding air. But if the oxygen for burning is supplied chemically, by an intimate mixing with an oxidizer such as saltpeter, the reaction happens far faster and with great gusto.

The sulfur, called brimstone by alchemists in the Middle Ages, plays a dual role: it facilitates detonation by lowering the temperature at which saltpeter ignites, and then it increases the speed and intensity of the ensuing chemical reaction.

Obtaining these three ingredients in sufficient purity and quantity wasn’t a trivial effort in today’s times, but it wasn’t overly difficult either. I would guess that any maker of legal age and average capability would have little trouble doing so. A short time on the internet visiting the websites of chemical supply companies yielded many likely sources.

Once I procured the saltpeter and sulfur, the final and most difficult step was obtaining the charcoal. This may run counter to intuition since bags of charcoal briquettes are piled up by the front door of any grocery. But bagged briquettes won’t work, adulterated as they are by chemical binders and additives. No, I had to make my own charcoal to obtain the purity required.

Roasting wood in the absence of air creates charcoal. I found I could obtain all the charcoal I needed by wrapping small hunks of willow wood in airtight aluminum foil, and leaving them overnight in the remains of the still-hot charcoal briquettes from an earlier cookout.

So now I had everything I needed. It was time to combine the three chemicals into the final stage of the project: real, live black powder.

Is This a Smart Thing to Do?

I can’t begin to tell you how many people laughed, turned pale, and/or ran away when I explained my intention to make gunpowder.

“That’s illegal!” they shouted.

“That’s what terrorists do!” they cried.

“That’s too dangerous!” they warned.

I beg to differ. In much of the United States and many other countries, possessing small amounts of black powder is assuredly not illegal. In most places, if you’re old enough, you can buy much larger quantities of higher-power, higher-quality black powder at any sporting goods store than you can make at home.

As for the terroristic potential of homemade black powder, it’s nearly nonexistent. Even underage delinquents have easier opportunities for finding materials with which to cause trouble than to go through the rather long and demanding processes required to make a primitive explosive like this.

And as for danger, well, of course it’s dangerous if you’re not careful. But so are driving a car and mowing your lawn. By working carefully and limiting quantities, I found I could reduce my risk to a level with which I was comfortable.

Now, I would love to explain in detail the recipe for black powder. And, I believe, so would MAKE magazine’s editors and publisher. Heck, so would the art director, the advertising staff, and the interns. Everybody at MAKE is onboard, with one exception: the company lawyer.

We live in a litigious society. Anybody can sue anybody for any reason. So, to allay the fears of our attorney, I’ll delve only into the procedure for the manufacturing of high-quality charcoal. Making your own charcoal is fun, easy, and worthwhile for reasons beyond making gunpowder. You can cook with it and you can draw with it. It’s worth doing at least once.

Making Charcoal

As noted earlier, charcoal briquettes are not usable for black powder because they have additives that are convenient for barbecuing steaks but lousy for making powder. Pure lump charcoal, or wood char, is simply wood roasted in the absence of air. Without air, the wood doesn’t oxidize or burn. Instead, it more or less bakes, the process removing water, oils, tar, and other volatiles, and turning what’s left into a dark, carbony residue.

After all the goo and moisture have been heated away, the wood char weighs about 20% as much as the original hunk of wood. This is pure charcoal, which burns hotter and more slowly than the original wood ever could.

1. Wrap small hunks of wood (willow wood is the traditional choice for gunpowder charcoal) in heavy-duty aluminum foil. Fold the edges tightly to make it airtight.

2. Poke a small hole approximately 1″ in diameter in one end of each hunk of foil-wrapped wood.

3. Line the bottom of a grill with regular charcoal briquettes and light them. When they’re covered with white ash, the coals are ready. (Incidentally, the white color comes from the addition of lime, which acts as a signal that the coals are ready. The lime is another reason you can’t use briquettes for black powder.) The number of briquettes you need depends on the amount of lump charcoal you wish to make. Keep in mind that a 5oz piece of wood becomes a 1oz piece of charcoal.

4. Place the wood bundles in the grill and cover them with hot briquettes.

5. Allow the briquettes to burn to ash. This will take several hours. When the briquettes have burned away, remove the wood bundles.

6. When cool, unwrap the charcoal and set aside. Your charcoal is ready to be used to grill steaks, draw fine art on canvas, or, if you’re the daring type, make black powder.

This Stuff Worked

The final steps involved in making black powder include measuring, mixing, and grinding. When I was finally finished, I scooped up my first-ever batch of powder and placed a little on a piece of paper to test it. With a match I lit the corner of the paper. The closer the flame came to the small mound of powder, the farther back I stood, unsure of what would happen when the fire reached the powder. There was a flash of orange light, an audible fizzle, and then a great plume of black smoke. This stuff worked.

I now had a small vial of homemade explosive. Strong, primal urges to use it hovered over me like smoke over a battlefield. Now I wanted to make something to blow up. And that meant making a firecracker.

I’m not stupid; I’ve seen enough pictures of mangled hands and empty eye sockets to not attempt an

M-80. The federal legal limit for explosives in commercial firecrackers is 50mg, which equates to a pile of powder a bit smaller than half an aspirin. The good thing about this is that at that size, your powder goes a long way.

I made a triangular paper case to hold the powder, and added a fuse. It took a while to figure out how to contain the expanding gas long enough to rupture the paper case so that a reasonable bang ensued. Once I mastered this skill, other gunpowder projects soon followed: blackmatch, quickmatch, rocket motors, and a few I don’t care to talk about in print.

A sense of pride and accomplishment washed over me, and I thought of myself as a bit like the Professor on Gilligan’s Island. I now know how to do something scientific as well as useful and practical.

And I understand the most important chemical discovery in the world with a degree of intimacy the average non-maker can never attain.

William Gurstelle

William Gurstelle

William Gurstelle is a contributing editor of Make: magazine. His new book, Defending Your Castle: Build Catapults, Crossbows, Moats and More is now available.

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