Ergo, in your post you quoted Harrit, who wrote:
„....primer paint – being basically a ceramic material – is chemically stable at temperatures up to 800 °C."
Harrit very probably referred to the
NCSTAR 1-3C report, Appendix A, where are these sentences: „
the paint (Tnemec, I.K.) was essentially ceramic coating...“ (p.433 and 437). I noticed these sentences several months ago. But here, NIST report was suprisingly, but apparently wrong (as well as Harrit). Since Tnemec primer for perimeter columns contained a lot of organic/polymer binder (alkyd-linseed resins and similar), it cannot be regarded as „ceramic coating“. It was just typical paint.
Justin39640, as for your post:
„Are we 100% sure that the paint was the structural steel's primer? Has anyone ever made a list of other possible sources?“ Yes, we have tried it, and this is a content of the thread „Origin of paint“. E.g., Oystein and BasqueArch calculated floor trusses surfaces painted by „Laclede primer“ and this paint simply should be very abundant in the dust, since painted area was huge and the paint was probably mostly stripped off during collapses. Generally, red primers applied on the construction steel were apparently the biggest available sources of such bi-layered red-gray chips.
Don't do it more complicated that it really is

) I think that the most of the Jim Millette XEDS data measured on freshly-cut red layers show: chips basically match the „spectral criteria“ of Bentham chips (a) to (d), see Fig. 12 and Appendix D in Jim's report, and are consistent with the „main culprit“, i.e. Laclede red primer. We just should sort, if they are some data for some red-gray chips which show that this and this particle is probably not Laclede paint. This is a quite good task for some guys e.g. from Germany

Also, I would like to know, if Jim Millette magnetically separated also some red-gray chips, which did not correspond to the spectral criteria of Bentham chips (a) to (d), according to him.
(I agree with Sunstealer, btw, some spectra are not really well readable in the Jim's report).
Btw, Jim Millette supposes that all his magnetically selected chips matching some basic criteria are the same material. In some individual cases, he may be wrong and it's just normal.
Chris: Jim Millette should read now our white-paper (written by Oystein) why Bentham chips (a) to (d) were particles of Laclede paint. It's up to him, if he includes this very plausible JREF theory into his conclusions. If not, interested readers can find the explanation in our white-paper (written by Oystein), which would gain a greater meaning and even some more audience in this way
Anyway, Jim Millette and Chris deserve many thanks again.
Among others, we have here more stuff to discuss, which is a sign that we all may live in rather too prosperous society which leads (among others) to the endless debates on apparent nonsenses (like evil nanothermite used for CD of WTC).