George Washington’s Blog 
Saturday, Aug 9, 2008
As everyone knows, the government initially tried to blame Iraq for the anthrax attack. One of the claims made was that the anthrax contained bentonite clay, which was also used by Iraqi anthrax bioweapons makers to “weaponize” the anthrax by decreasing the tendency of anthrax spores to clump together. (Clumping makes them less deadly since clumping reduces the amount of spores which end up in the target’s lungs).
The government later disclaimed that assertion. However, the FBI now claims that the killer anthrax contained silicon. Silicon can be used as an anti-clumping agent to weaponize anthrax.
For example, McClatchy  notes:
“Some of Ivins’ former colleagues also dispute the FBI’s assertion that he had the capability to mill tiny anthrax spores and then bind them to silicon particles, the form of anthrax that was mailed to the office of then-senator Tom Daschle, D-S.D.”
(Article continues below)
And as New Scientist  writes, FBI agents “mention a ‘silicon signature’ for the anthrax in the envelopes with no further comment. Silica may be used to weaponise spore powders.”
Evidence for the theory that the anthrax used in the attacks was coated with anti-clumping agents also comes from a a 2001 CBS  article:
“When technicians at the Army biodefense lab in Fort Detrick, Md., tried to examine a sample from the Daschle letter under a microscope, it floated off the glass slide and was lost. “
Anthrax would normally clump, so the fact that it “floated off the glass slide” points to the anthrax being treated with anti-clumping and anti-static agents.
Why is this important?
It takes very sophisticated equipment and processes  to coat something as small as an anthrax spore with anti-clumping agents:
“Only a sophisticated lab could have produced the material used in the Senate attack. This was the consensus among biodefense specialists working for the government and the military. In May 2002, 16 of these scientists and physicians published a paper in the Journal of the American Medical Association, describing the Senate anthrax powder as “weapons-grade” and exceptional: “high spore concentration, uniform particle size, low electrostatic charge, treated to reduce clumping” (JAMA, 1 May 2002, p. 2237).”
Indeed, the anthrax sent in the letters was coated with a very rare, high-tech glass polymer nanomaterial :
More revealing than the electrostatic charge, some experts say, was a technique used to anchor silica nanoparticles to the surface of spores. About a year and a half ago, a laboratory analyzing the Senate anthrax spores for the FBI reported the discovery of what appeared to be a chemical additive that improved the bond between the silica and the spores. U.S. intelligence officers informed foreign biodefense off icials that this additive was “polymerized glass.” The officials who received this briefing—biowarfare specialists who work for the governments of two NATO countries—said they had never heard of polymerized glass before. This was not surprising. “Coupling agents” such as polymerized glass are not part of the usual tool kit of scientists and engineers making powders designed for human inhalation. Also known as “sol gel” or “spin-on-glass,” polymerized glass is “a silane or siloxane compound that’s been dissolved in an alcohol- based solvent like ethanol,” says Jacobsen. It leaves a thin glassy coating that helps bind the silica to particle surfaces.
Silica has been a staple in professionally engineered germ warfare powders for decades. (The Soviet Union added to its powders resin and a silica dust called Aerosil —a formulation requiring high heat to create nanoparticles, says Alibek. U.S. labs have tested an Aerosil variant called Cab-O-Sil, and declassified U.S. intelligence reports state that Iraq’s chemical and biological warfare labs imported tons of both Cab-O-Sil and Aerosil, also known as “solid smoke,” in the 1980s). “If there’s polymerized glass [in the Senate samples], it really narrows the field [of possible suspects],” says Jacobsen, who has been following the anthrax investigations keenly. “Polymerized glasses are exotic materials, and nanotechnology is something you just don’t do in your basement.”
By March 2002, federal investigators had lab results indicating that the Senate anthrax spores were treated with polymerized glass, and stories began to appear in the media. CNN reported an “unusual coating” on the spores, and Newsweek referred to a “chemical compound” that was “unknown to experts who have worked in the field for years.” When Science asked the FBI about the presence of polymerized glass in the Senate powder, an FBI spokesperson said the bureau “could not comment on an ongoing investigation.”
(Silica is the principle component of glass. The FBI is apparently misspeaking when it is now saying that the anthrax contains “silicon”).
But Dr. Ivins was a vaccine researcher, not a weapons maker. Moreover, Ivins was working in a lab where – according to his co-workers and supervisors – people went in and out all night checking on experiments (so they presumably would have seen suspicious activity by Ivins, had there been any), and Ivins did not have access to the extremely high-tech equipment which would have been necessary to produce the weaponized anthrax. He wasn’t one of the count-on-one-hand group of people who knew how to coat coat anthrax spores with anti-clumping agents.
Moreover, Ivins was one of the lead researchers helping the FBI investigate the anthrax murders. Remember, CBS wrote “when technicians at the Army biodefense lab in Fort Detrick, Md., tried to examine a sample from the Daschle letter under a microscope, it floated off the glass slide and was lost.” This implies that the Ft. Detrick scientists, including Ivins, had never handled this kind of weaponized anthrax before.
The media has rightly been questioning whether or not Ivins knew how to dry anthrax. And his colleagues have rightly been asking whether Ivins, a vaccine expert, could have made anthrax as pure and concentrated as the killer anthrax (for example, a former director of the bacteriology division at Ft. Detrick said the anthrax sent to Daschle was “so concentrated and so consistent and so clean that I would assert that Bruce could not have done that part “).
But the media is missing another large part of the story . . . it is very doubtful that Ivins knew how to weaponize the anthrax spores with advanced anti-clumping agents.