Thursday, September 22, 2016

A look at the explosives used in the New York bombing: officials had detected the explosive hexamethylene triperoxide diamine (HMTD) in devices related to the attack.

   New York City Mayor Bill de Blasio and New York Governor Andrew Cuomo stand over a dumpster mangled in the Sep. 17 bombing.
Credit: Justin Lane/Newscom

A look at the explosives used in the New York bombing
Some reports suggest bombs contained a combination of Tannerite and HMTD
By Ryan Cross


Initial reports about a device used in Saturday’s bombing in New York City suggested the explosive could have been a commercially available material called Tannerite. Stories from the Associated Press and New York Times reported the claim, citing anonymous officials involved in the investigation of the attack that injured 31.

But, on the basis of the material’s properties, explosives experts and the makers of Tannerite doubt it alone could have caused the explosion. A subsequent report from the New York Times seemed to confirm these doubts, indicating that officials had detected the explosive hexamethylene triperoxide diamine (HMTD) in devices related to the attack.

The suspected bomber, Ahmad Khan Rahami, was arrested after a shootout in New Jersey on Monday. He allegedly set off bombs in New Jersey and in New York on Saturday. According to news reports, anonymous officials identified Tannerite at the New York bomb site, and a second report linked HMTD to both bombings.

Tannerite, made and sold by Tannerite Sports, is used to produce exploding targets for long-range shooting practice. The targets explode when hit by a bullet, allowing shooters to hear and see that they’ve successfully made the shot. Occasionally, “tannerite” is used to describe similar products.

An exploding Tannerite target consists of an 8:1 ratio of oxidizer to catalyst, which come in separate containers and are mixed and shaken together prior to use. The Tannerite patent says that, in the optimal composition, the oxidizer contains 85% ammonium nitrate powder by weight, and 15% ammonium perchlorate. The catalyst is 90% explosive grade aluminum powder, 5% titanium sponge, and 5% zirconium hydride.

Jimmie C. Oxley, an explosive specialist at the University of Rhode Island, says that using Tannerite wouldn’t require chemistry training. “It is one of the less hazardous explosives to work with,” she says. But she doubts it was the sole explosive used in New York.

“It is impossible,” says Daniel Tanner, CEO of Tannerite Sports. Only a high-velocity bullet travelling at a minimum of 610 meters per second can trigger their exploding targets to go off. Tannerite is also resistant to fire, friction, and hard impacts. It cannot be merely jolted into exploding, suggesting that normal bomb triggers wouldn’t set it off. Furthermore, Tanner says finding aluminum or ammonium nitrate residue isn’t enough to say Tannerite was used. “Tannerite is not a compound,” he says. “It is a trademark.”

“Tannerite is not going to go off by itself,” Oxley says. “It is very stable stuff. You are going to have to put a strong initiating shock into it. And that could be provided by HMTD.”

HMTD is an organic explosive similar to triacetone triperoxide, the explosive used in the 2015 Paris attacks and the 2016 Brussels bombings. “HMTD is not stable and not nice stuff. You can easily set it off,” Oxley says. “To use HMTD there has to be some synthesis involved,” she says. Thus far, there are no reports as to how Rahami could have made or obtained HMTD for use in the bombs.

Anyone can buy Tannerite online or at sporting goods stores and gun shops. It is not regulated by the Bureau of Alcohol, Tobacco, Firearms & Explosives because the oxidizer and catalyst parts alone are not considered explosives. One state, Maryland, bans the sale, use, and ownership of exploding targets without an explosives license.

Law enforcement officials in the past have considered exploding targets as potential sources of bomb-making materials. A 2013 FBI bulletin on exploding targets concluded that they could serve as an alternative source of ammonium nitrate, which was used to make the bombs involved in the 1996 Oklahoma City bombing. 


Maker of Tannerite explosive rejects link to New York bombing

A New York Police Department (NYPD) robot retrieves an unexploded pressure cooker bomb on 27th Street, hours after an explosion nearby in New York City, New York, U.S. September 18, 2016. REUTERS/Lucien Harriot
By David Ingram | NEW YORK

The maker of an explosive linked to bombs in New York and New Jersey over the weekend said on Tuesday there was no proof its Tannerite product had been used in the attacks and said it would be a poor choice for a bomb.

Tannerite, an explosive powder commonly used at gun ranges to make targets blow up, or a similar substance was one ingredient in the homemade bombs that exploded in Manhattan's Chelsea neighborhood, wounding 29 people, and in Elizabeth, New Jersey, according to law enforcement officials involved in the investigation.

Tannerite Sports LLC, based in Oregon, said its product is designed only to explode when struck by a speeding bullet and would not be a good material for use in a detonated bomb.

"It's disgusting that the media spews out a brand name with no proof or thought," company founder Dan Tanner said in an email to Reuters.

Law enforcement officials said they did not immediately know if the bombs used Tannerite, one of its competitors or a homemade version with the same two ingredients, ammonium nitrate and aluminum powder. Some media have named the explosive as Tannerite.

Exploding powders are not regulated by the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives because they are generally sold in a kit with the two ingredients separated. The ingredients on their own do not explode.

Ahmad Khan Rahami, 28, is suspected in the weekend bombings, including Saturday's blast in Chelsea, another bomb found in Chelsea that did not detonate, the bomb found in Elizabeth, New Jersey, and a bomb that went off Saturday morning in Seaside Park, New Jersey. U.S. authorities were investigating whether he had accomplices or was radicalized during trips to Afghanistan and Pakistan.

A Tannerite company expert said the product would make a poor ingredient for a bomb because it is meant to explode only at target practice.

"You have to shoot it," corporate investigator Steve Yerger said in a phone interview. "We certainly would want to know if someone's found a way to ignite Tannerite without a high-powered rifle."

There were no reports that a firearm was used in the New York or New Jersey bombings.

The remnants of the bombs that exploded in Chelsea and Elizabeth were examined at the FBI lab in Quantico, Virginia, two U.S. officials participating in the investigation said.

The lab determined the detonator was the compound hexamethylene triperoxide diamine, or HMTD, which one official said is a poor choice because it is relatively unstable and sensitive to heat and shock.

The explosive was a combination of ammonium nitrate and aluminum powder, said the officials, who agreed that the substance is very difficult to ignite.

Tannerite has tested its product many times but never combined it with HMTD and did not know what the result would be, Yerger said. Adding Tannerite to HMTD would make no sense, he said, because HMTD is a more powerful explosive.

It was not immediately known where the bomb maker obtained the explosives, although Tannerite is easily available in most of the United States.

The bombs included pipe bombs and pressure-cooker bombs similar to those used in the April 2013 Boston Marathon bombing, which killed three and injured 260. The Boston bombs were backed with black powder from commercially manufactured fireworks, a lower-powered explosive.

Tannerite is usually mixed at a firing range, creating a target that will explode and give gun owners instant feedback on their marksmanship.

The materials can be mixed in large quantities, and videos proliferate online of people using the powder and a gun to blow up vehicles, live hogs and other targets.

Exploding targets have been banned in some U.S. national forests, out of fear they contribute to wildfires and are a threat to public safety.

Last year, Tanner told firearms website "No terrorist has used Tannerite to harm anyone, because the unique properties of the product simply does not lend itself to such use."

Homemade bombs are often backed with nails, BB pellets or other small metal objects that serve as shrapnel, increasing their deadliness.

Yerger contended that blaming his company if its product was used in a bomb was akin to blaming a nail manufacturer.

"Are you going to ban nails?" he asked.

(Reporting by David Ingram; Additional reporting by Mark Hosenball and John Walcott in Washington; Editing by Scott Malone and Leslie Adler)