The bomb that exploded Saturday in New York City used an explosive called Tannerite, according to news reports. Until now, Tannerite has mostly been known to target shooters. Now it’s being implicated in a terrorist attack. Here are answers to some questions about an explosive you might not have heard of and its role in this unfolding story. 
 
 What is Tannerite? 
 
 Tannerite is the brand name of a binary explosive often used as a rifle target. Binary explosives are two-part mixtures of components that aren’t explosive on their own. The original patent for Tannerite describes a mixture of ammonium nitrate, ammonium perchlorate and powdered aluminum and a few minor ingredients. Steve Yerger, an investigator for the company, says the current proprietary formulation uses just the ammonium nitrate and powdered aluminum. 
 
 Generic mixtures of ammonium nitrate and powdered aluminum, sometimes called ammonal, are sometimes also called Tannerite, like calling all facial tissues Kleenexes. 
 
 Why are people using this stuff? 
 
 Tannerite is popular for target practice because it produces a loud bang and a puff of smoke when hit with a fast-moving bullet. That makes it more obvious—and more exciting—when you hit the target than, say, shooting a piece of paper. 
 
 The reason they use Tannerite specifically is because it’s easy to get and relatively safe. Because the two components aren’t themselves explosive, the Federal government doesn’t regulate Tannerite like it does black powder or TNT. You can buy it online or in stores, and the individual components are available on their own. 
 
 Okay. Is it dangerous? 
 
 It can be. Although Tannerite was designed to produce a relatively small explosion for safety, people have been seriously hurt and even killed using it. In most cases that happened when it was detonated inside a container, which fragmented and sent shrapnel flying at the victims. 
 
 Binary explosives do have an inherent degree of safety, in that they aren’t explosive until the two parts are mixed. 
 
 And how does it work? 
 
 A chemical explosive has two fundamental components: a fuel and an oxidizer. The fuel releases energy when it reacts. The oxidizer provides the oxygen atoms the fuel needs in order to react. In your fireplace, wood is the fuel and the air around us is the oxidizer. 
 
 In the patented recipe for Tannerite, the fuel is aluminum powder with some titanium. The oxidizer is a mixture of ammonium nitrate and ammonium perchlorate, the key part being the “ate” on the ends of those words. That means they contain oxygen, in this case bound to nitrogen and chlorine atoms respectively. Ammonal, the generic version is usually just the aluminum powder and ammonium nitrate. 
 
 When mixed together, the components need a certain amount of energy to set off the explosive reaction. In the case of Tannerite, that comes from the kinetic energy of a fast-moving bullet. Oxygen atoms leave nitrate and perchlorate and bind to aluminum atoms to form aluminum oxide. That’s the stuff that gives untreated aluminum its rough, ashy look. 
 
 Like all explosive reactions, it works because the products are more stable than the starting components. 
 
 Going from less stable compounds to more stable compounds releases energy in the form of heat and light. In the case of Tannerite or ammonal, the reaction also produces a gas, whose expansion in a sealed container adds to the explosive power of a bomb. 
 
 Ammonium nitrate sounds kind of familiar. Where have I heard that name before? 
 
 Ammonium nitrate had figured in high-profile explosions before. It was used in the 1995 Oklahoma City bombing and was the cause of an accidental explosion in 2013 in West, Texas that killed 15 people. 
 
 Explosives use nitrogen-containing compounds like ammonium nitrate because they produce nitrogen gas. TNT, trinitrotoluene, is a famous example. Nitrogen gas, which makes up almost 80% of our atmosphere, is two nitrogen atoms joined by a triple bond. That triple bond is incredibly strong, meaning it takes a huge amount of energy to break. Conversely, the bond releases a huge amount of energy when it forms. In Tannerite or TNT, the formation of nitrogen gas is one source of their explosive energy. 
 
 So Tannerite was the explosive in the New York City bombs? 
 
 Maybe. First, to be clear, the name Tannerite is appearing in news stories attributed to unnamed law enforcement sources. Tannerite residue was reportedly found on the two bombs discovered in New York over the weekend. Other bombs linked to the suspect, Ahmad Rahami, who is now in custody, may have used different explosives. These reports may be wrong in part or whole. 
 
 The company that makes Tannerite is skeptical. Steve Yerger, the company investigator, says he has not been able to confirm with the FBI or other law enforcement agencies that Tannerite was in fact found in the New York bombs. What’s more, he says he doesn’t know how it could have been used. 
 
 In the company’s tests, says Yerger, Tannerite can only be detonated by the impact of a high-velocity bullet. A burning fuse, an electrical current, a hammer blow; none of those will work, according to him. There have been no reports that a gunshot was used to trigger the bomb that exploded in New York on Saturday. 
 
 What Yerger says is entirely plausible. He hasn’t shared the results of the tests he is talking about, but explosives can be and are made so that they only explode in certain ways. “That’s in keeping with a lot of explosive materials,” says Dave Welch, a senior explosives expert at Ramora UK, which does bomb disposal. Welch could not confirm Yerger’s assertions about Tannerite specifically. 
 
 There are other ways to detonate an aluminum oxide and ammonium nitrate bomb though. The bombs in this test of ammonal done by scientists at the Los Alamos and Sandia National Labs were set off with standard detonators and boosters used to produce a shock with enough energy to explode the mixture. We'll need more information from law enforcement agencies before we know what happened in Chelsea. 
 
 Correction: This post has been updated with information from the Tannerite company about the product's formula. ||||| NEW YORK (CBSNewYork) — Investigators say the bomb that went off in Chelsea contained residue of an explosive compound that is easy to find. 
 
 CBS2’s Alice Gainer reported Tannerite, which is the brand name, is unregulated and that anyone can buy it. The compound is sold as a mix of two chemicals and it creates high explosives when combined. 
 
 An instructional video on Tannerite Sports’ website explains how the exploding target works. 
 
 “Pour the contents of the catalyst packet into the mixing container,” the instructor said in the video. 
 
 The Bureau of Alcohol, Tobacco, Firearms and Explosives defines binary explosives as pre-packaged products consisting of two separate components – typically an oxidizer like ammonium nitrate and a fuel like aluminum or another metal. 
 
 The ATF doesn’t regulate the compound because separately, the chemicals don’t meet the definition of explosive. 
 
 In response to the Chelsea explosion, Tannerite Sports said it is working to determine if their product was definitely used in Saturday’s explosion. 
 
 “As far as our knowledge and independent testing results show, our product can only be set off by a successful high-power rifle shot directly to the target; and in addition that once done it vaporizes as it is an endothermic product,” the company said in a statement. 
 
 Manny Gomez, a former FBI agent and security expert, said the company is being on the “defensive.” 
 
 “They’re being defensive. The bottom line is not if that was used, the bottom line is that product, as well as other products, are easily accessible and could detonate a pressure cooker,” Gomez explained. 
 
 He continued, “Just like you set off a round in a rifle simply by pushing a little snap, every round has its own little detonator, it’s a similar thing with a pressure cooker. The only thing is that they used old-fashioned flip phones as a method of detonation.” 
 
 Gomez compared the product to gasoline put in cars, noting people use it responsibly, but if used inappropriately, that could light a building up. 
 
 “It’s just something we have to be aware of that these terrorists are very clever at finding out what components can come together and make an improvised exploding device,” Gomez said. 
 
 Though they don’t regulate it, ATF has put out advisories about binary explosives before. 
 
 They ask people to report any unusual activity with these materials. For example, if someone is attempting to buy a large quantity while knowing very little about the product. 
 
 The suspect in the bombings, Ahmad Khan Rahami, will be charged with five counts of attempted murder. ||||| Skip in Skip x Embed x Share CLOSE A visual timeline of the bombing attacks and attempted bombing attacks in New York and New Jersey over the weekend of Sept. 17th and 18th. USA TODAY 
 
 NEW YORK, NY - SEPTEMBER 18: FBI agents review the crime scene of remnants of bomb debris on 23rd St. in Manhattan's Chelsea neighborhood on September 18, 2016 in New York City. An explosion that injured 29 people that went off in a construction dumpster is being labeled an "intentional act". A second device, a pressure cooker, was found four blocks away that an early investigation found was likely also a bomb. (Photo by Stephanie Keith/Getty Images) (Photo: Stephanie Keith, Getty Images) 
 
 The bomb that exploded in Manhattan on Saturday contained residue of Tannerite, a legal product used primarily for target practice. Tannerite explodes when struck by a bullet from a high-powered rifle so ranges put it on targets as a way to prove a target has been struck. 
 
 The brand-name product is defined as a "binary explosive" by the federal Bureau of Alcohol, Tobacco, Firerams and Exposives (ATF). This means it's sold in two inert pieces, said Jimmie Oxley, a chemistry professor at the University of Rhode Island. It is not an explosive until the two parts are mixed, Oxley said. 
 
 Even when two separate parts – ammonium nitrate and aluminum powder – are mixed, the compound won't explode until it's hit by the bullet, she said. 
 
 Tannerite cannot be set off by a smoldering fuse, an electronic fuse, an electrical current, an open flame, impact with a hammer or even a low-velocity handgun, according to Steve Yerger, a corporate investigator for Tannerite. 
 
 It's a very stable product, he said. 
 
 A federal law enforcement official who was not authorized to speak publicly about the ongoing investigation confirmed that investigators found Tannerite residue the bomb that exploded in Chelsea, injuring 29 people on Saturday night. 
 
 Tannarite makes it easy for shooters at a range to easily determine whether their shot hit its intended target, Yerger said. Tannerite is sold in many sporting goods stores. It's also available on the Tannerite website. 
 
 "We feel horrible that Tannerite has been associated with the bombing," Yerger said, 
 
 On its Facebook page Monday afternoon, the company said that it was aware of the bombing in New York and the explosive devices found in New Jersey. "The entire staff of Tannerite stands together in the abhorrence and unintended use of all products that are misused for violence and hate," the Facebook post said. 
 
 The ATF does not regulate the sale and distribution of the two chemicals used in Tannerite and similar products, even when sold together in binary "kits," the ATF said. 
 
 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY Ahmad Rahami: What we know about the suspected bomber | 0:41 Everything we know about the suspected bomber Ahmad Rahami. USA TODAY 1 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY WATCH: Interview with Linden bar owner Harinder Bains | 0:44 Linden bar owner Harinder Bains, who found the bombing suspect asleep in his doorway. USA TODAY 2 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY Photographer describes the capture of Ahmad Khan Rahami | 0:47 A photographer recounts the moment he witnessed the arrest of NYC bombing suspect Ahmad Khan Rahami, after a shootout in New Jersey. 3 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY Timeline of attacks in New York and New Jersey | 1:08 A visual timeline of the bombing attacks and attempted bombing attacks in New York and New Jersey over the weekend of Sept. 17th and 18th. USA TODAY 4 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY Video shows suspect being loaded into ambulance | 1:09 Witness video captured the moment Ahmad Khad Rahami was loaded into an ambulance in Linden, New Jersey following a gun battle with police. Authorities say the Afghan immigrant is the main suspect behind explosions in New York and New Jersey. (Sept. 19) AP 5 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY Commuters unfazed despite NYC bombing | 0:54 New York City commuters Monday morning said they weren’t afraid or overly concerned to travel despite the Chelsea weekend bombing and other bombs found in New Jersey. 6 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY Mayor de Blasio: No evidence of terror cell | 1:41 Investigators probing bomb blasts in New York and New Jersey say they've found no evidence so far that the suspect in the attacks was part of a broader terrorist cell. (Sept. 19) AP 7 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY Mayor de Blasio: NYC bombing was an act of terror | 1:09 New York City Mayor de Blasio, along with other NYC officials, provided more details around the bombing that injured 29 people. Even though officials arrested a suspect, the mayor promised a stronger, visible NYPD presence throughout the week. 8 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY FBI speaks about capture of terror suspect | 1:22 Newark, NJ, FBI Special Agent in Charge Tim Gallagher speaks about the investigation that lead to the arrest of Ahmad Khan Rahami in Linden, NJ. THOMAS P. COSTELLO 9 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY Obama tells Americans, 'Don't succumb to fear' | 0:41 Following the explosions in New York City and New Jersey and the stabbing attack in Minnesota, President Obama reminded Americans to stay strong. 10 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY Suspected N.Y., N.J. bomber taken into custody | 0:36 Ahmad Khan Rahami, the suspect wanted in connection to the New Jersey and New York City bombings, is now in custody. USA TODAY 11 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY N.J. residents recall N.Y. suspect as 'friendly' | 1:07 Police are seeking 28-year-old Ahmad Khan Rahami, a naturalized U.S. citizen from Afghanistan, in connection to Saturday's bombing in New York. His last known address was in Elizabeth, New Jersey, where the FBI executed a search warrant Monday. (Sept. 19) AP 12 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY NYPD identify 'wanted' man in Manhattan bombing | 0:55 NYPD says a 28-year-old man is wanted for in connection to the New Jersey and New York City bombings. 13 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY Raw: Video of Elizabeth, New Jersey Explosion | 1:03 A suspicious device found in a trash can near a New Jersey train station exploded early Monday as a bomb squad was attempting to disarm it with a robot, officials said. (Sept. 19) AP 14 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY Man helps injured after New York bombing | 1:14 Cell phone video shows a man helping several women who were injured in Saturday night's bombing in New York. (Sept. 18) AP 15 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY Raw: Surveillance shows moment of NYC explosion | 1:53 Surveillance video provided to the Associated Press by Orangetheory Fitness Chelsea, showed people running and debris flying moments after an explosion was set off. (Sept. 18) AP 16 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY Mayor calls New York City explosion a bombing | 1:00 New York City's Mayor Bill de Blasio says an explosion that rocked a Manhattan neighborhood Saturday night was caused by a bomb. But de Blasio said Sunday that authorities don't yet know who made it, who set it off or the motivation behind it. (Sept. 18) AP 17 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY 5 things to know about NYC explosion | 0:56 A powerful blast from an explosive device injured at least 29 people in New York City's popular Chelsea neighborhood on Saturday night. USA TODAY NETWORK 18 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY Raw surveillance of NYC blast | 0:37 Surveillance cameras captured the NYC Chelsea explosion. USA TODAY 19 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY Clinton, Trump react to New York blast | 1:08 A deliberate explosion rocked one of the most fashionable neighborhoods of New York on Saturday night, injuring 29 people, one seriously, a week after America's financial capital marked the 15th anniversary of the 9/11 attacks. Video provided by AFP Newslook 20 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY Trump appears to pre-empt NYC cops on blast | 0:32 Donald Trump appeared to pre-empt New York City officials when he declared Saturday evening that a "bomb went off" in New York City before officials had released details. (Sept. 18) AP 21 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY RAW: Witness assists injured at scene of Chelsea explosion | 1:18 RAW: Witness assists the injured at scene of a powerful explosion from a explosive device the injured at least 29 people in New York's popular Chelsea neighborhood on Saturday. Video courtesy of Ramón Lopez. Ramón Lopez / NorthJersey.com 22 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY New York blast 'intentional' but no known terror link: NY Mayor | 0:58 New York's Mayor Bill de Blasio says a blast in the Chelsea neighborhood of Manhattan, which left 29 people injured, was 'intentional' but that there was no evidence of a terror connection. Video provided by AFP Newslook 23 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY Raw: NY Governor Arrives At Scene of Explosion | 1:09 New York Governor Andrew Cuomo arrived at the scene of an explosion that rocked a crowded Manhattan neighborhood and injured 29 people the night before. (Sept. 18) AP 24 of 25 Skip in Skip x Embed x Share CLOSE EXPLOSION IN CHELSEA NEIGHBORHOOD OF NEW YORK CITY Raw: More than two dozen hurt in New York explosion | 1:09 Police and firefighters are at the scene of a possible explosion in New York City, and authorities say at least 25 people suffered minor injuries. (Sept. 17) AP 25 of 25 Last VideoNext Video Ahmad Rahami: What we know about the suspected bomber 
 
 WATCH: Interview with Linden bar owner Harinder Bains 
 
 Photographer describes the capture of Ahmad Khan Rahami 
 
 Timeline of attacks in New York and New Jersey 
 
 Video shows suspect being loaded into ambulance 
 
 Commuters unfazed despite NYC bombing 
 
 Mayor de Blasio: No evidence of terror cell 
 
 Mayor de Blasio: NYC bombing was an act of terror 
 
 FBI speaks about capture of terror suspect 
 
 Obama tells Americans, 'Don't succumb to fear' 
 
 Suspected N.Y., N.J. bomber taken into custody 
 
 N.J. residents recall N.Y. suspect as 'friendly' 
 
 NYPD identify 'wanted' man in Manhattan bombing 
 
 Raw: Video of Elizabeth, New Jersey Explosion 
 
 Man helps injured after New York bombing 
 
 Raw: Surveillance shows moment of NYC explosion 
 
 Mayor calls New York City explosion a bombing 
 
 5 things to know about NYC explosion 
 
 Raw surveillance of NYC blast 
 
 Clinton, Trump react to New York blast 
 
 Trump appears to pre-empt NYC cops on blast 
 
 RAW: Witness assists injured at scene of Chelsea explosion 
 
 New York blast 'intentional' but no known terror link: NY Mayor 
 
 Raw: NY Governor Arrives At Scene of Explosion 
 
 Raw: More than two dozen hurt in New York explosion 
 
 Mixing binary components together constitutes manufacturing explosives, according to the ATF: "Persons manufacturing explosives for their own personal, non-business use only (such as personal target practice) are not required to have a federal explosives license or permit," the ATF said on its website. 
 
 "However, when the binary components are combined, the resulting mixture is an explosive material," the ATF warned. The ATF issued an advisory last year, warning that these products are "high explosives and should be treated with caution and in accordance with manufacturer’s instructions." 
 
 According to Tannerite, the company's corporate investigator is working to determine whether the product was used in the bombing. 
 
 "At this time we are unable to validate the allegations due to it being an ongoing investigation," according to the company's Facebook page. 
 
 Though federal regulations are lacking, one state is attempting to regulate the sale of Tannerite: 
 
 After a failed attempt last year, Indiana state senator Jim Merritt will again introduce a bill in January 2017 that would prohibit the sale of Tannerite to customers younger than 18 and also require retailers to place the products behind the counter or in a locked display case. 
 
 Though Merritt said he's all for target practice, this is a "common-sense approach," he said, noting several instances of Indiana residents hurt by flying shrapnel in Tannerite-related explosions. 
 
 Contributing: Kevin Johnson, USA TODAY 
 
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– A legal product that can be purchased online or at a sporting goods store was used in the bomb that went off in Manhattan Saturday, USA Today reports. Tannerite is a product typically used for target practice; it is placed on targets and explodes when struck by a bullet from a high-powered rifle. It's sold in two inert parts (ammonium nitrate and aluminum powder), neither of which is regulated by the ATF. Once those two parts are mixed together, it only explodes if a bullet hits it and is considered very stable, a corporate investigator for Tannerite says. Tannerite residue was found inside the bomb that exploded in Chelsea, a federal law enforcement official tells USA Today. A post on the company's Facebook page Monday reads, "The entire staff of Tannerite stands together in the abhorrence and unintended use of all products that are misused for violence and hate." It goes on to note that its investigator is working to verify that Tannerite was indeed used in the bomb. A former FBI agent tells CBS News Tannerite appears to be "on the defensive." "It’s just something we have to be aware of that these terrorists are very clever at finding out what components can come together and make an improvised exploding device," he says. Forbes has more on the science behind Tannerite.