Origin of the paint that was found as red-gray chips - any ideas?

[Ivan Kminek]

1) Sorry for the double post, it was caused by the sudden connection failure.

2) Here is an another XEDS of Sr-containing mixture measured up to 20 KeV http://www.freepatentsonline.com/20110117367.pdf, Fig. 3. Again, Sr K-level peaks (between 14 and 16 KeV) are much smaller than Sr L-level peak at 1.8 KeV.

3) Let me suppose that chip (a) was a Laclede primer particle. According to Oystein's calculation, there was about 40x more of iron than that of chromium (by wt.) in Laclede primer. Since iron and chromium have almost the same atomic number, they should have similar intensities of K-level peaks. No wonder than, that chromium K peak at 5.4 KeV (theoretically 40 times smaller than iron peak) is so little in the expanded XEDS spectrum of a chip (a) (Fig. 5, Harrit's whitepaper) in comparison with Fe K-peak at 6.3 KeV. Problem is: I can perhaps explain why the chromium peak is so little by this way, but this is not a proof that strontium chromate was present in the chip (a)

(Sorry for possible errors concerning the XEDS peaks nomenclature)

 

[leftysergeant]

Bear in mind, too, that kaolin is not always pure aluminum silicate. There may be inclusions of such other minerals as nacrite and dickite.

Sorry if that confuses things at all.

 

[Sunstealer]

That Harrit whitepaper adds very little to the "original" paper at Bentham, except for detailing what tnemec is. Of course we already know that chips a-d are not tnemec, so he is on the wrong boat for most of the time.

On page 6, he false claims that "Magnesium was never observed". His own Fi.6, an XEDS of chip e (MEK lalala...) has an unlabelled peak at about 1.25keV, which is quite likely the K-alpha level of Mg. The same peak is found in the XEDS that Jones had done on actual tnemec from a WTC column; I showed that in my blog (fig. C).

Now I disagree with you that Cr and Sr have readily visible peaks in Harrit's Fig. 5: He puts the labels where he would expect to see peaks, but they aren't really discernibly there, except for one possible Cr peak. However he magnified only one of the 4 XEDS charts for chips a-d. Going back to the Bentham paper, Figure 7 has tiny tiny blips at 5.4keV for chips b and d, which corresponds with k-alpha of Chromium. a and c are practically flat there. Unfortunately, those spectra end at 10keV, so we don't know if any Strontium peaked beyond 14keV.

Unfortunately, I am not convinced that Harrit's data points to LaClede standard paint - the Cr-signal is woefully weak, and the Sr non-existent for all I can tell.

Maybe Sunstealer can shed a bit more light here.

He won't do that personally, the SEM/EDX software will do it. The only reason to relabel the spectra is when you know you have a certain element present but the software is labelling it as something else due to an overlap. Cr and Sr are definitely present because both the K-alpha and K-beta peaks are being identified.

Unfortunately we don't have detailed spectra for samples a-d and the spectra in the Harrit et al paper certainly isn't that great.

Is it proven that LacClede standard joist paint was used on the WTC? NIST NCSTAR 1-6B section says:

4.2.7 Primer

The trusses supplied by Laclede Steel were shop primed during production using an electro-deposition process. The formulation for the primer was designated as Formula LREP-10001 and was found in Laclede files (see appendix B). The exact formulation could not be reproduced due to current environmental considerations. A stock steel primer, manufactured by Sherwin Williams and designated Type B50NV11 (recommended by Isolatek International, the manufacturer of the sprayed fire-resistive material used in these tests and in the original construction of the WTC towers was determined to be an acceptable substitute. The primer was field applied to the trusses after assembly in the ULN and ULC fire test facilities.

I'm unsure what that exactly means apart from the spray on fire resistant company recommended a different paint due to environmental concerns. Did Laclede Steel produce and prime the steel trusses for the WTC?

 

[Sunstealer]

Let's see.
According to specification, LaClede steel paint is 4% Strontium Chromate.
Strontium Chromate is SrCrO₄. Molar mass of SrCrO_{4 is 87.62 + 52 + 4x16 = 203,62 Strontium is 87.62/203,62 = 43% by weight of its chromate, or 43%x4% = 1.7% by weight of the pigments. Chromium is 52/203,62 * 4% = 1.0% of the mass of all pigments. Oxygen another 64/203,62 * 4% = 1.3% Similarly: Iron Oxide (Fe2O3) is 30,1% oxygen and 69,9% iron, and (multiplied by 55%) provides 16.5% oxigen and 38.5% iron to all pigments Aluminum Silicate is Al2Si2O5(OH)4 That adds 8.6% Aluminium, 8.9% Silicium and 22.9% Oxygen to the pigments. Sum of elements in the pigments thus: O: 40.7% Fe: 38.5% Si: 8.9% Al: 8.6% Sr: 1,7% Cr: 1.0% (H: 0.6%) The binder would mainly add C and O, and dilute the metals. Now, I don't know how to interprete the heights of the peaks. It is my understanding that mass or count of elements corresponds to peak height only roughly. Harrit's spectra show Si-peaks just slightly higher than Al, which matches the above mass proportions perfectly, but why does he find "more" S and Ca than Sr? S in the binder?}

_{Great analysis. Your comparison between Al and Si is spot on and is exactly what I was banging on about in 2009. It's the ratio between certain peaks that gives the insight to analysis, not just how high all the individual peaks are, that give you information as to what material you are seeing. I had a little look at the Laclede Standard Joint Paint composition Vehicle (71.5% of total so 28.5% is pigment by weight) Unmodified Epoxy Amine 45% Deionized Water and Amine 55% Sulphonamides are sulphur based amines used as plasticisers. So Sulphur could be part of the binder. As for the Calcium then that's probably found in the aluminosilicate.}

 

[Ivan Kminek]

Thank you, Sunstealer, for your explanation concerning invisible Sr and Cr peaks)

As regards primers: when I read these NIST report paragraphs I understood that original WTC floor trusses were painted with the Laclede primer. But since it contained environmentally unfriendly chromium and strontium, this primer was replaced with Sherwin Williams stuff in the case of floor joists assembled and tested in NIST.

To Leftysergeant: Although we know for sure that some "aluminum silicate" was present in the Laclede paint, we do not know if this was kaolinite or any other such stuff.

 

[Sunstealer]

So why are strontium peaks in region over 10 KeV in Fig. 5 (whitepaper of Harrit) marked in XEDS of a chip (a), although invisible? I have no access to chemical journals from home so I depend on some googling now.

Software will label them.

Up to now, I found this paper https://www.corrdefense.org/Academia Government and Industry/XXI-BROWN-TUCKER.pdf , in which strontium chromate was used as some kind of coating. There is a Fig. 4 with a XEDS spectrum containing also strontium and chromium signals, in the region 0 to 20 KeV. Although this picture is of a very bad quality, I can judge from this that Sr signal at cca 1.8 KeV is much, much stronger than Sr signals at ca 14.2 and 15.8 KeV. Simultaneously, this strong signal at 1.8 KeV could be hidden in Fig. 5 of Harrit's whitepaper, since there are very strong signals of Al and Si in this region. Perhaps, Harrit's device found this comparatively strong Sr signal, but marked only those very weak Sr signals at 14.2 and 15.8 KeV. I can also judge from the Fig. 4 (link above) that chromium signal at 5.4 KeV is significantly weaker than the strontium signal at ca 1.8 KeV (both elements are present in the same molar amounts in strontium chromate). This is in accordance with the fact that strontium has a higher atomic number than chromium.

Of course, it does not answer your question, but it could provide some hints why are Sr signals in Fig. 5 (Harrit) invisible (if the chip (a) is a particle of Laclede paint).

Yes, any Sr peak @2KeV will be drowned out by other elements but we know it's there because the correlating peaks at around 14.1 and 15.8KeV are present.

I'm not convinced yet, but I think it's a possibility. We need more data which I doubt we'll find unless anyone knows where we can obtain complete EDX spectra for samples a-d.

It's a far better bet than thermite!

 

[Ivan Kminek]

Sulphonamides are sulphur based amines used as plasticisers. So Sulphur could be part of the binder.

There is no mention on the sulfonamide or any other sulfur compound in the Laclede binder formulation. They could be there in some minor amounts but we have no proof.

As for the Calcium then that's probably found in the aluminosilicate.

Thanks for this

 

[Sunstealer]

Bear in mind, too, that kaolin is not always pure aluminum silicate. There may be inclusions of such other minerals as nacrite and dickite.

Sorry if that confuses things at all.

I agree, kaolin is unlikely to be pure. There is also evidence of other possible particles in the Harrit paper, notably in Fig 8b.

 

[Oystein]

I am mightily impressed - we are making progress! I agree we won't be able to call of the search until we get better data, especially beyond that 10keV graph limit, and, better yet, a hand on actual floor joist primer residue.

However, our theory is a much much better fit with the data than Harrit's


I have two more question that we should look into:

1. The relative amount of vehicleigments = 71.5%:28.5% - is that wet paint or cured paint, and how will that change over 30 years of time?
2. The paint specification for the LaClede joists calls for a coating thickness of 1mm. I suppose that's after curing. Would we expect to find flaked-off paint chips to still be about 1mm thick, and if so, is that matched by Harrit's images?

 

[Oystein]

Bear in mind, too, that kaolin is not always pure aluminum silicate. There may be inclusions of such other minerals as nacrite and dickite.

Sorry if that confuses things at all.

No confusion at all, in fact, that's excellent thinking.
As for now, we should not claim outright that a Ca-signal would come from kaolin, period. That would be conjecture. But it's certainly worth looking into: Shoul be possible to find typical analysis results for ready-to-use kaolin for industrial purposes.

 

[Oystein]

...
Yes, any Sr peak @2KeV will be drowned out by other elements but we know it's there because the correlating peaks at around 14.1 and 15.8KeV are present.
...

For the record, here are some Edge Energies (keV) of the relevant elements in that region:

Strontium (₃₈Sr):
K 16.1049995
L1 2.21600008
L2 2.00699997
L3 1.94000006
M 0.35800001
K-alpha 14.1639996
K-beta 15.8339996
L-alpha 1.80599999
L-beta 1.87199998

Silicium (₁₄Si):
K 1.83899999
L1 0.118000001
L2 0.0997999981
L3 0.0992000028
M 0.
K-alpha 1.74000001
K-beta 1.83200002
L-alpha 0.
L-beta 0.

I found no other common element with a peak near 1.8keV.

So any Sr might / would indeed be masked by the Si-peak. Would the expected amount of Sr increase that peak significantly?

 

[Sunstealer]

I am mightily impressed - we are making progress! I agree we won't be able to call of the search until we get better data, especially beyond that 10keV graph limit, and, better yet, a hand on actual floor joist primer residue.

However, our theory is a much much better fit with the data than Harrit's


I have two more question that we should look into:

1. The relative amount of vehicleigments = 71.5%:28.5% - is that wet paint or cured paint, and how will that change over 30 years of time?
2. The paint specification for the LaClede joists calls for a coating thickness of 1mm. I suppose that's after curing. Would we expect to find flaked-off paint chips to still be about 1mm thick, and if so, is that matched by Harrit's images?

Cough. Actually 1 mils = 25.4µm (25.4 microns). It's easily mixed up with mm or mil. I checked this as soon as I saw it on the Appendix B paint info. The red layer on the chips from the Harrit paper look to be around 15µm thick. The paint spec says 1 mils ±0.2 mils which would equate to a minimum of 20.32µm.

1 mils = 1 thou or 1 thousandth of an inch.

I'm not sure whether it's dry or wet percentages.

 

[Oystein]

Cough. Actually 1 mils = 25.4µm (25.4 microns). It's easily mixed up with mm or mil. I checked this as soon as I saw it on the Appendix B paint info. The red layer on the chips from the Harrit paper look to be around 15µm thick. The paint spec says 1 mils ±0.2 mils which would equate to a minimum of 20.32µm.

1 mils = 1 thou or 1 thousandth of an inch.

I'm not sure whether it's dry or wet percentages.

Argh! Americans and their stupid non-SI units! I never heard of mils - that's 1/1000th of an inch, okay.

Sooo the layer thickness is in the right ballpark, but not spot-on.

 

[Oystein]

By the way:
From Harrit e.al. "Active Thermitic Material Discovered in Dust from the 9/11 World Trade Center Catastrophe" page 9:

An FEI XL30-SFEG scanning electron microscope
(SEM) was used to perform secondary-electron (SE) imaging
and backscattered electron (BSE) imaging. The SE imaging
was used to look at the surface topography and porosity
of the red/gray chips, while the BSE imaging was used to
distinguish variations in average atomic number, Z. The microscope
was also equipped with an EDAX X-ray energy
dispersive spectrometry (XEDS) system. The XEDS system
uses a silicon detector (SiLi) with resolution better than 135
eV. The spectrum resolution was set to 10 eV per channel.
Operating conditions for the acquired XEDS spectra were 20 keV beam energy (unless otherwise specified) and 40-120
second acquisition time (livetime). XEDS maps were acquired
using the same system at a beam energy of 10 keV.

We should maybe just ask him directly to release graphs for all chips including the region 10-20keV?

 

[Sunstealer]

Argh! Americans and their stupid non-SI units! I never heard of mils - that's 1/1000th of an inch, okay.

Sooo the layer thickness is in the right ballpark, but not spot-on.

Hehe. I think you can blame us Brits for that one. "thou" is a very common engineering term for 1/1000in and you'll often hear "ten thou" and "twenty thou" being referenced, usually by older engineers even when the drawing is in mm!

So you'll often hear something like, "that's comma five mill (0,5mm), so what's that in old money? erm twenty thou"

1mm = 40 thou is how I remember it as a rough approximation.

I've been bought up in the metric era, but culturally we'll still use miles, yards, feet and inches and thou, and rulers all have cm and inches. You get used to it. Although mils is a new one for me aswell!

In one job I had to work in metric for the RB199 engine designed by UK/Germany/Italy and then imperial for Pegasus engine which was pre-metric sometimes on the same day.

 

[The Almond]

For the record, here are some Edge Energies (keV) of the relevant elements in that region:

Strontium (₃₈Sr):
K 16.1049995
L1 2.21600008
L2 2.00699997
L3 1.94000006
M 0.35800001
K-alpha 14.1639996
K-beta 15.8339996
L-alpha 1.80599999
L-beta 1.87199998

Silicium (₁₄Si):
K 1.83899999
L1 0.118000001
L2 0.0997999981
L3 0.0992000028
M 0.
K-alpha 1.74000001
K-beta 1.83200002
L-alpha 0.
L-beta 0.

I found no other common element with a peak near 1.8keV.

So any Sr might / would indeed be masked by the Si-peak. Would the expected amount of Sr increase that peak significantly?

Hey, thought I'd add a few things to the debate. The Sr/Si issue is what we refer to as a pathological overlap. The elements overlapping with Si are Rb, Sr, Ta and W. You're right that Sr is the most likely (by far) culprit here, but we have to be careful about comparing relative peak heights and trying to make compositional estimates based on that.

Working with X-rays in the region around Si is very complicated, and the correction factors for determining composition in those lighter elements (O, Na, Mg, Al and Si) are usually quite large (> 30 %). Oxygen absorbs silicon X-rays very efficiently, but the situation is made much more complicated by the presence of other metals, especially iron. As for the Sr K peaks, the ratio of the K line to the L line is about 0.014 or about 1.5% That means your L line is much stronger than your K line by a factor of about 100 to 1.

I went ahead and simulated using Monte Carlo calculations based on a bulk, homogeneous material, which would be pigment only. The most striking thing is that Sr is a total no-show. If I expand the vertical scale up a lot, I can start to see the hints of a Sr peak, but even as an experienced analyst, I would probably miss it. The only hint that Sr might be present is the extended tail on the high energy side of the Si peak.

 

[Oystein]

Hey, thought I'd add a few things to the debate. The Sr/Si issue is what we refer to as a pathological overlap. The elements overlapping with Si are Rb, Sr, Ta and W. You're right that Sr is the most likely (by far) culprit here, but we have to be careful about comparing relative peak heights and trying to make compositional estimates based on that.

Working with X-rays in the region around Si is very complicated, and the correction factors for determining composition in those lighter elements (O, Na, Mg, Al and Si) are usually quite large (> 30 %). Oxygen absorbs silicon X-rays very efficiently, but the situation is made much more complicated by the presence of other metals, especially iron. As for the Sr K peaks, the ratio of the K line to the L line is about 0.014 or about 1.5% That means your L line is much stronger than your K line by a factor of about 100 to 1.

I went ahead and simulated using Monte Carlo calculations based on a bulk, homogeneous material, which would be pigment only. The most striking thing is that Sr is a total no-show. If I expand the vertical scale up a lot, I can start to see the hints of a Sr peak, but even as an experienced analyst, I would probably miss it. The only hint that Sr might be present is the extended tail on the high energy side of the Si peak.

[qimg]http://www.internationalskeptics.com/forums/imagehosting/thum_127714e4988a200a42.png[/qimg]

Thanks for showing me how little I know...

I notice that your bulk sim, which contains no O and C, has pretty wild Cr-peaks around 600eV:
Chromium:

L1 0.681999981
L2 0.583800018
L3 0.574100018​

These would compete with (among others?) the K-level of O at 537eV.
Now Harrit e.al. do show O (537eV) and C (284eV) - so where is Cr in their graphs? I seem to notice little bumps for Cr at K-alpha = 5.414keV at least for chips a, b and d, but the big ones are missing...

 

[Ivan Kminek]

Figs. 5 and 7 (Harrit's whitepaper) should be inserted here for comparison. (I still do not know how to do it).

Almond, thanks a lot for your valuable simulation and remarks, I did not know that you are an expert on XEDS. Now I think that your simulated XEDS spectrum of Laclede paint and the real XEDS spectrum of chip (a) are pleasingly similar, at least at first glance (except deliberately missing C peak in the simulation)

I notice that your bulk sim, which contains no O and C, has pretty wild Cr-peaks around 600eV:

So this big peak at ca 0.6 KeV belongs to Cr, not O? (It is not easily readable and I do not know if oxygen was included in that simulation). If this is chromium peak, there might be again probably overlap of two peaks (O and Cr) in the real spectra. You mentioned that chromium peaks at 5.4 KeV are visible as little bumps even in the unexpanded spectra of chips (b) and (d), so it is a real pitty that we cannot look at these spectra as expanded. This could be more convincing as for Cr.

The paint specification for the LaClede joists calls for a coating thickness of 1mm.

I already mentioned in the contribution #66 here that the paint layer used in NIST tests (therefore comparable with the thickness of the original paint) was about 1 mil (0.025 mm) thick.

The relative amount of vehicleigments = 71.5:28.5% - is that wet paint or cured paint, and how will that change over 30 years of time?

I do not know if this was calculated for the cured or wet paint, but for the dry paint, I would not expect any substantial change in composition of this crosslinked epoxide even during 30 years (except perhaps some oxidation). But this is just my guess.

 

[Ivan Kminek]

So I understand that Cr and Sr were very probably present in the chip (a) since their peaks were labeled by the XEDS device. Can we (in principle) prove that red chips were Laclede primer particles in some better/independent way?

1) We can ask HenryCo for some red chips from the dust. Since XEDS spectra are not ideal for the detection/determination of Cr and Sr in this particular mixture, we could turn to some other method for the determination of these metals, e.g. mass spectrometry or atomic absorption spectrometry.

2) We can collect Laclede paint somewhere. Its XEDS spectra should be very similar to that of red chips to support our working hypothesis, but the comparison of its microscopic pictures with those of red chips studied by Harrit et al. would be perhaps more important. I still think that a quite crucial and simple proof can be obtained by DSC measurement under air: if Laclede particles show the same/similar exotherms at the same experimental conditions as for chips in Harrit's paper... it would be great I repeat: as a polymer chemist, I am using our DSC service (with a very fine person in charge) ca once a month. It should be no problem for me to arrange such measurements. It is also no problem to ask people from the microscopic department here to look at the unburned and burned Laclede paint.

(Sorry that I am repeating some things again here)

 

[Oystein]

Ivan,

some more ideas what we can do:

The gray layer has so far received no attention in this thread, and very little attention by Harrit e.al.
If we find more information on what the LaClede paint was painted on (type of steel), then maybe we can predict what we'd expect to find, and compare with the data by Harrit, however little that is.

I think we have by now collected enough observations and ideas for a first draft or summary of a "paper". Well, blog post. If I find the time and consentration...


Hey, have any of you guys noticed that our resident truthers (tmd, Marokaan, RedIbis...) and 9/11-agnostics (femr2, ...) are staying out of this thread? Sole exception is Bill Smith, who carefully avoids adressing the evidence we are collecting