Reply #5: Representativeness of the samples.

[Carefulplease]

The steel samples examined by NIST are not representative of temperature distributions in the burning WTC Towers in 9/11 for many reasons.

(1) The selection criteria involved many factors besides possible fire exposure. Samples representative of typical failure modes or aircraft impact damage were also sought.

(2) When there was forensic evidence that the heat exposure or mechanical damage could have been incurred in the rubble pile the samples were discounted. This leaves very few unambiguous samples. Much of the steel of the impact floors was crushed and buried deep under the steel and material of many floors above (tens of thousands of tons) and was exposed to very hot underground fires for many weeks.

(3) The paint cracking method only worked when there was enough paint remaining to perform the analysis. This was seldom the case. Most often there was no paint remaining at all. This skewed the results since the column areas exposed to the most extreme temperatures and to aircraft debris impacts weren't likely to have had as much paint remaining on them as other samples had.

(4) The sample size is much too small for the results to be statistically significant.

This list is not intended to be exhaustive.