- The Washington Times - Thursday, June 28, 2001

Very few people have a deep knowledge of chemistry, and that's too bad, because when the Fourth rolls around and fireworks start exploding and illuminating the skies, they can't answer that one burning question: What makes those things go boom?

The periodic table holds the key. Without the chemistry that goes into the creation of each firework, none of us would be able to enjoy the annual celestial light show.

"A firework is chemistry in action," says John A. Conkling, a professor of chemistry at Washington College in Chestertown, Md., and technical director for the American Pyrotechnics Association (APA). The association, based in Bethesda, supports and promotes safety standards for all aspects of fireworks.

It's easy enough to find out the ingredients that go into one of those dazzling displays, and Mr. Conkling could write them on the back of a matchbook in a flash. Of course, he wouldn't do that — it's too easy for youngsters to make their own — but it goes something like this: KNO3+Al+Fe = gold sparks.

That is, it's a combination of potassium nitrate, aluminum and iron — plus a little magic, which Mr. Conkling deliberately won't mention.

Every firework has its own blend of chemical compounds, he says.

"The key to a successful firework is a chemical mixture that burns and produces colors, the sparks and the other types of visible effects we associate with fireworks," says Mr. Conkling, 57.

"All of the things you see in the sky are a result of chemical reactions," the pyrotechnics chemist says.

The role of the chemist is to develop the mixtures that will burn and produce, let's say, a beautiful crimson or vibrant green flame that bursts into a resplendent chrysanthemum with its perfectly shaped spheres, or a fountain that showers the night with luminous white sparks.

"The various colors are produced by specific chemical elements that are heated to high temperatures in the fireworks flame," he says.

"For example, the element strontium will produce a beautiful red flame color. Pieces of charcoal will produce beautiful orange sparks, and metal powders such as aluminum produce white sparks," says Mr. Conkling, who holds a doctorate in chemistry from Johns Hopkins University.

Fireworks connoisseurs judge the quality of a fireworks presentation by a color that's difficult to achieve, he says.

"The most difficult color effect to achieve is a deep blue flame. That's the ultimate challenge for all fireworks manufacturers because there is no chemical mixture that burns with the production of a deep, intense blue flame. So the best we can do is a moderate blue with a pyrotechnic mixture," he says.

The sound is produced by packing an explosive mixture such as black powder into a tightly sealed container. When it's ignited, the mixture burns violently and ruptures the package. Then there is a bright flash and the characteristic "kaboom," he says.

Several cartridges are packed inside one firework device. When the firework bursts in the air, the fuses to the multiple explosive components are set off, producing a series of kabooms.

The native Baltimorean has been mixing bits of this and bits of that since childhood. He found science scintillating. He filled his home with smoke on countless occasions, much to his parents' chagrin. Yet, he says, they tolerated his scientific experiments. Pyrotechnics, the science of producing visible or audible effects through the burning of a chemical mixture, piqued his curiosity in 1969.

Today, Mr. Conkling teaches summer courses in the chemistry of pyrotechnics at Washington College. Many of his students are government employees whose work involves safety. Others are in the business of materials such as propellants and explosives. He says he teaches the only pyrotechnics courses in the United States.

Although fireworks have been around for about 1,000 years, Mr. Conkling says the chemistry of fireworks heated up about 75 years ago. Advances have been made in equipment that enable chemists to investigate principles and get to the root of the science of fireworks.

"Today, one of the big advances has been an instrument called a thermal analyzer, which lets us observe the temperatures at which fireworks reactions occur. That has primarily helped us with safety and understanding the ignition of these materials," he says.

"On the other hand, a spectrometer enables us to look at a flame and determine the chemical species that are contributing the color in the flame. And this has dramatically helped us to produce better color quality and fireworks," he says.

• • •

The initial development of fireworks — whether the glitter of a sparkler or a monumental fireworks display — all begins in the laboratory. Of course, Mr. Conkling says, chemists work with ounces of materials rather than the larger quantities fireworks manufacturers use.

Mr. Conkling says some of the hot areas of research include developing mixtures that produce very little smoke but still produce beautiful colors. That's been a goal in the field for years because smoke can interfere with the viewing of fireworks at indoor concerts and sporting events and outside activities. New fuels are being tested to produce fewer solid-reaction products, the chemist says.

"A second area where a lot of work is going on is the development of what is called pattern shells, which are aerial fireworks that explode in the sky and form a pattern such as a heart or a star," he says. For example, Mr. Conkling says, the stars are attached to a sheet of paper to form the desired pattern, and then a bursting charge is placed carefully around the pattern to retain the desired shape as the stars fly out into the sky.

There is another big advance in fireworks, but it doesn't entail changes in the chemical components. It's all engineering, and it's hot. It involves setting off the fireworks with the help of computer technology, Mr. Conkling says.

The goal, he says, is to choreograph the fireworks with music. The sounds and sights are synchronized.

For example, Mr. Conkling says, as the words "And the rockets' red glare" from Francis Scott Key's "Star Spangled Banner" reverberate, a volley of red fire bursts in the air — immediately followed by a loud boom, boom, boom, boom, as the song continues with "the bombs bursting in air."

"That's very hard to do if you're running around and lighting fuses on the ground. Using the computer, we are able to precisely control the timing of discharge," he says. A well-choreographed display is just spectacular, Mr. Conkling says.

When it comes to launching breathtaking Fourth of July celebrations, Matt Shea, the producer for Atlas Advanced Pyrotechnics Inc., keeps audiences' heads to the sky. Next Wednesday, Independence Day, will be no exception — there will be plenty of explosive and dazzling moments on the Mall.

Fifteen thousand pounds of fireworks will light up the sky to celebrate America's birthday, Mr. Shea says. This year, the pyrotechnics company in Jaffrey, N.H., has created some special shells for its audience and the country's new president, he adds.

"People will see different effects from last year. We have the standard patriotic theme, the large chrysanthemums and the peonies. And this year we have a lot of domestic shells that were specially made for the show. There will be azaleas and lots of other splendid types of flowers," the pyrotechnician says.

A barrage of chrysanthemums, peonies and a 15-second scene of brilliant white spiders consisting of 300 shells of varying sizes will light up the night skies and begin the celebration at 9:10 p.m., he says.

The boom doesn't bother Mr. Shea a bit. Atlas Advanced Pyrotechnics Inc. has entertained Washington's discerning fireworks enthusiasts for the past five years.

Although the fireworks Mr. Shea and other professionals like himself use for fireworks displays are different from backyard fireworks, he urges folks to follow the professionals' lead.

"The most important things professionals do that others should do is never underestimate what you are lighting. Always light **the firework** and walk away. Every piece of fireworks has a safety fuse on it. Whether it's consumer fireworks or professional fireworks, there's a timing fuse on it. The safety fuse allows the person to get a safe distance way from the fireworks. Also, professionals will always have water available to put out fires," he say.

Fireworks are showing up everywhere, from cakes to commercials.

"In 1976, the country's Bicentennial, the total consumption of fireworks in the United States was 30 million pounds. Last year, we used over 200 million pounds, so business is booming," Mr. Conkling says, smiling.

Safety matters. It's a top priority for chemists such as Mr. Conkling and at fireworks manufacturing companies. Dazzle can turn deadly. Fireworks manufacturing is a federally regulated industry, and the use of fireworks is controlled locally. Mr. Conkling says the industry's safety record has improved greatly during the past 25 years.

Martha Lockwood agrees. She is a firecracker when it comes to fireworks safety. As executive director of the National Council on Fireworks Safety (NCFS) in Bethesda, she is charged with getting the word out, especially at this time of year. NCFS is dedicated to the safe enjoyment of fireworks in the United States.

Safety has improved, Ms. Lockwood says. "In 1990, there were 67.6 million pounds of fireworks consumed in the United States. There were 17.7 injuries per 100,000 pounds." That means there were about 12,000 injuries, according to the Consumer Product Safety Commission, she says.

In 1999, 156.9 thousand pounds of fireworks were used in the United States, roughly 21/2 times as much as was used nine years earlier. Fireworks-related injuries totaled 8,500, a dramatic drop. The use of fireworks has gone up 250 percent, and the injury rate has decreased to less than one-third of what it was in 1990, Ms. Lockwood says.

Chemists sparkle over 4th of July

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