It's way past its expiration date.
There were several tests that Harrit could have done to rule out thermite (as proper hypothesis testing requires), but he did none of them. In complete contravention of proper scientific investigation, not only did he try his damnedest to find ways of making the chips look like thermite while avoiding any experiments that would have ruled out thermite, but he simply ignored or dismissed with sophistry any result that said otherwise. He heated some chips in air and found that they ignited at a temperature well below the ignition temperature of thermite (more in the range of carbon-based materials, in fact). He also found that some chips had energy densities (energy per weight) greater than is theoretically possible for thermite (but a rather ordinary energy density for many carbon-based materials -- like maybe the matrix that the iron and aluminum were embedded in). If Harrit still suspected that his samples were thermite, despite this contrary evidence, he should have at least tested in an inert atmosphere, since thermite doesn't need oxygen from the air to burn, but either he didn't do that or he didn't like the result. Nonetheless, he concludes that it must be some highly engineered form of thermite that we just don't understand -- a conclusion which simply does not follow from the data he collected.
Since the thermitic reaction with iron oxide requires elemental aluminum which isn't already bound to other molecules, another test he should have done was to test for elemental aluminum. Instead, he tries to infer it from a rather dubious test on a chip that didn't get any other testing. Tests and micrographs that he did on other chips showed aluminum in mysterious (to Harrit) flat plates, but they were quickly identified (on sight by people who had seen the stuff before) as Kaolinite, aluminum silicate, "China clay", which cannot participate in a thermitic reaction. (And it is certainly not any engineered nano-particle, either.) It is, however, sometimes added to paint as a pigment. Oddly enough, so is iron oxide.
The paper itself notes that the most obvious hypothesis was that these were paint chips, and yet the tests that they claim ruled out paint are ludicrously inadequate (e.g. they just tested some paint that Steven Jones scraped off the the BYU stadium bleachers). They apparently did not even attempt to find out what kind of paint was used as rust-proofing on the WTC steel. If they had just checked that first, they might have noticed that the paint used on the floor joists had components identical to the chips, and they might have avoided the embarrassment they have caused themselves and the "truth movement."
"Truthers" claim this paper was published in a "peer-reviewed" journal, but funny thing about that: The publisher, Bentham Open, contrary to the standards of any reputable journal, allowed Harrit to name his own referee, and we now know that it was David Griscom, a notorious thermite advocate whom Harrit thanks in the paper for his contributions and advice on how to do the experiments. Two volunteer editors for the Open Chemical Physics Journal resigned because they were not informed that the paper would be published, and they strongly objected to it. And now, Bentham has dropped that journal from its lineup.
Of course, you would reject technical criticisms from any "non-believer," but even a fellow "truther" said, "There is much wrong with this article. It would not have passed my expert peer review in its published state."
"Truthers" like to claim the authors are experts, but in fact, none of them had any experience with forensic chemical analysis, and it shows in the paper's obvious shortcomings. But then, an independent study by an actual materials expert who does forensic chemical analysis for a living, Dr. James Millette, found:
In summary, red/gray chips with the same morphological characteristics, elemental spectra and magnetic attraction as those shown in Harrit et al.1 were found in WTC dust samples from four different locations than those examined by Harrit, et al.1 The gray side is consistent with carbon steel. The red side contains the elements: C, O, Al, Si, and Fe with small amounts of other elements such as Ti and Ca. Based on the infrared absorption (FTIR) data, the C/O matrix material is an epoxy resin. Based on the optical and electron microscopy data, the Fe/O particles are an iron oxide pigment consisting of crystalline grains in the 100-200 nm range and the Al/Si particles are kaolin clay plates that are less than a micrometer thick. There is no evidence of individual elemental aluminum particles detected by PLM, SEM-EDS, or TEM-SAED-EDS, during the analyses of the red layers in their original form or after sample preparation by ashing, thin sectioning or following MEK treatment.
Carbon-based epoxy resin with kaolin and iron oxide pigments -- a.k.a. paint -- but no elemental aluminum, and no elemental aluminum means no thermitic reaction, period. And yet, some "truthers" just can't let this bullshit go.
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