The contradiction can be easily resolved:
They used TWO or more different thermite preparations, of which the red-gray chips that ignite at about 430 °C
* are only one kind
**. The authors have variously claimed post-publication that this red-gray material may not be from the explosive charges (they are never even described as being "explosive"), but perhaps "fuses" or "nano-matches".
Essentially this boils down to AE911truth + Jones/Harrit not committing to any testable theory, really.
* Except that this is not even true: the claim "
When the red/gray chips were heated to about 430° C. (806° F.), they ignited" does not follow from the data it supposedly interprets. The DSC plots shown in Harrit et al 2009 are Figures 19 and 29:
This shows on the right, in red, the reaction of actual nano-thermite when heated: It starts off endotherm until about 360 °C, then exotherm reactions develop until a peak at ca. 535 °C, when specific power is roughly 5 W/g. This peak power, 5 W/g, must therefore count as "
releasing relatively large amounts of energy very fast". The blue curve - one of the Harrit/Jones chips, peaks at 440 °C with ca. 10.5 W/g, but rises above zero already near 200 °C. The truthers evidently think that 10 W/g counts as "
releasing relatively large amounts of energy very fast"
Now compare this to the other chips they tested:
I have added the horizontal and vertical lines.
We see that the green and black curves rise above zero very soon, and surpass 10.5 W/g at a temperature slightly below 400 °C. It is wrong to say they "
ignite" at "
about 430 °C", when two of the chips are already "
releasing relatively large amounts of energy very fast" at temperatures below 400 °C. In fact, these two plots rise so steadily and smoothly towards their peaks that it is difficult to pinpoint where they ignite at all. This is indicative of a material that has no fixed ignition point. I'd assume this paint has a binder made from several organic materials - such as linseed oil plus resin plus whatever. What happens there is that the organic matrix decomposes by and by (is cracked into smaller molecules) as temperature increases, and the released gasses (benzene, CO, methane, H2, whatever) ignite at various rates and ignition points.
Also, when reading these DSC plots, you need to understand that the x-axis (°C) is actually equivalent to a time-scale: The samples were heated at a constant rate of 10 °C/min, and net energy flow is determined relative to an inert control probe and plotted on the y-axis. So with every 10 °C that you move to the right in the plot, a minute has passed! When, for example, the green curve exceeds 10 W/g at 400 °C, then peaks at 430 °C and 21 W/g, 3 full minutes have passed between these two events! It will go on releasing more than 10 W/g another 2 to 3 minutes. This is a tiny sample, we are talking about a chip that's 0.1 mm thin and something like 1 mm long - and it (the gree curve) burns for 5 minutes at a greater rate of energy release than the peak of the blue curve. Is this a powerful material? By no stretch of the imagination! It merely smolders peacefully!
** Except that the Harrit/Jones paper describes 6 (six) different kinds of chips, all of which would be "nano-thermite", or so the reader is lead to believe.