Very probably, yes. The thing is, the NIST report does not claim, absolutely definitively, what it is, because no one took sample of the stream of metal at the time if was flowing. They "conclude" that it probably was, because it's a logical explanation of the observed metallic flow.
Lacking a direct sample as evidence, they could only speculate and give likely or probable explanations for observations that were made.
Keep in mind, this is only relevant to people like Jones because they are making the wildly improbable claim that it was molten structural steel, instead of aluminum. By claiming it is not aluminum that was observed, they still don't have an explanation of how steel would melt to the point of pooling and running down the exterior, but doing so without the much lower melting point aluminum melting and being observed to melt, despite the abundance of that material along the exterior areas of the structure, and from the plane, itself.
(From the same link in the question) -
NIST reported (NIST NCSTAR 1-5A) that just before 9:52 a.m., a bright spot appeared at the top of a window on the 80th floor of WTC 2, four windows removed from the east edge on the north face, followed by the flow of a glowing liquid. This flow lasted approximately four seconds before subsiding. Many such liquid flows were observed from near this location in the seven minutes leading up to the collapse of this tower. There is no evidence of similar molten liquid pouring out from another location in WTC 2 or from anywhere within WTC 1.
Photographs, as well as NIST simulations of the aircraft impact, show large piles of debris in the 80th and 81st floors of WTC 2 near the site where the glowing liquid eventually appeared. Much of this debris came from the aircraft itself and from the office furnishings that the aircraft pushed forward as it tunneled to this far end of the building. Large fires developed on these piles shortly after the aircraft impact and continued to burn in the area until the tower collapsed.
NIST concluded that the source of the molten material was aluminum alloys from the aircraft, since these are known to melt between 475 degrees Celsius (900 degrees Fahrenheit) and 640 degrees Celsius (1,200 degrees Fahrenheit)—depending on the particular alloy—well below the expected temperatures (about 1,000 degrees Celsius or 1,800 degrees Fahrenheit) in the vicinity of the fires. Aluminum is not expected to ignite at normal fire temperatures and there is no visual indication that the material flowing from the tower was burning.
So the NIST looks at this observation, with the claim that it was nefarious because an office fire would be able to melt steel, and points out that was a ready and expected source of aluminum for the office fires to melt at the observed temperatures. No magical explanations needed.
As far as Steven Jones not being able to replicate an ignited skyscraper melting an airplane with some aluminum, a skillet, a propane torch and some wood chips to throw into it...... that's more than a bit bizarre to think that's any kind of debunking. Interesting that he didn't try adding plastic and/or glass, which would actually melt under heat. Perhaps he wasn't all that interested in seeing whether the theory could be confirmed.
The idea that molten aluminum would only appear to be silver is utter nonsense, without any kind of evidence to back it up. This seems to be common knowledge among anyone who has dealt with metals.
Name: Bob Status: student Grade: 9-12
Location: MS Country: USA Date: Fall 2010
Question: What color will any metal be (zinc, for example) radiate when it is heated to its melting point?
Molten metals usually seem to have simple thermal-glow colors. Oxide crystals, glass, metal salts, and organic chemicals show much more variety and color-saturation.
Most liquid (melted) metals are silvery, which is high reflectivity and low emissivity, so they try not to radiate much of any color. But, usually the reflectivity is less than 90%, so the emissivity is >10%, so some glowing will happen. Impurities on the surface, such as oxidation or slag or carbon, by being dark instead of silvery, could enable additional radiation. And if the impurity added a color of its own, the glowing could pick up some color bias.
The metal can only glow in the visible range if it is hot enough for a black body to glow red, orange, yellow, white, or hotter. Look up black-body radiation and color temperature. Molten Aluminum at 660degC, for example, is just barely hot enough to glow deep dull red in a dark room.
Your question does not have a simple answer because there is no single answer. Here is a (short) list of factors involved: 1. The temperature. Any object, regardless of and independent of its composition will have a "color" from dull red to blue-white that depends only its temperature. If you want to track this source down search the internet for "black body radiation" and look at the X-axis scaled in wavelength between 400 (blue) to 700 (red) nanometers, which is the wavelength range of visible light. Also you can see the "red" end by looking at the burners on an electric stove. 2. The color also depends upon reactions with atmospheric gases, especially oxygen and nitrogen, which are the major components of air. The oxides and / or nitrides that form are usually less dense than the metal and tend to float to the surface. Oxides and nitrides tend to be white to gray, but this is also piled on top of the black body radiation, and some oxides--iron for example, may be red to black, depending upon which oxide is present. These colors apply at room temperature. What happens at the melting point of iron is difficult to say. 3. Sodium is an impurity that is difficult to exclude, since it is a component in many materials, e.g. glass to mention just one. Sodium has intense yellow emissions at 569 & 590 nanometers (called the sodium D-lines). These can obscure any other visible emissions by other metals. Of course the presence of carbon can give the characteristic orange of a carbon flame.
As I said this is a short list. There are no doubt a number of others depending upon the metal, its purity, and the wide range of melting temperatures of metals.
Some conspiracy addicts have tried to invoke the "thermite reaction" in the 9/11 tragedy, and part of their claims has to do with the color of flames from the Twin Towers. However, those claims are not credible if the chemistry is examined carefully and impartially. They know the answer they want and will bend the data to fit their presumptions.
Department of Energy "Ask A Scientist!" Archive