Another "Blue Star" Topic

[Crazy Swede]

No, arsenic was not neglected but it did not show in the spectrum. Most probably because it is a weak emission and my guess is that it drowns in everything else. I spoke to Dominykas Juknelevičius about this today as a matter of fact.

 

I see what you mean that the carbonate can break down to carbon dioxide and carbon monoxide but is the latter such a strong reducing agent that it would steal an oxygen from the oxidiser in a blue composition, that typically is lean on oxygen?

 

If it does, how could that simulate the proposed indigo coloured emission from arsenic? Or do you simply mean that Paris green is somewhat of a coolant compared to copperoxichloride for example?

[cmjlab]

Swede,

 

I admit it's been a couple years since I read that study, and it was informative. Didn't the author concede that the Hardt Sulfur Blue and KCLO3/Paris Green were still "viewed" as the best in appearance from a practical application standpoint amongst the pyrotechnic community?

 

I also don't recall, but did he include the Clive Jennings-White Blue Strobe (Guanidine Nitrate formula)?

 

Charles

[JAWChemist]

If you go to Wikipedia where the flame test of the various substances is treated, the data that I have mentioned is highlighted. reading the writing you reported it is explicitly said that the formula contains green Paris Spectrum analysis of arsenic has been neglected. The carbonate absorbs oxygen because when the structure of the molecule breaks down and releases the carbonate group, this group is transformed into co2 and a co which absorbs part of the oxygen from the oxidizer, lowering the combustion temperature.

Could you copy the link and post It?

[cmjlab]

Here is the link to the PDF document:

 

https://www.google.com/url?sa=t&source=web&rct=j&url=https://epub.ub.uni-muenchen.de/75968/1/prep.202000114.pdf&ved=2ahUKEwixm8CMxJ38AhXpqXIEHWvPAfUQFnoECCIQAQ&usg=AOvVaw3Kq6WpUZiPoZtUBsPuPbek

 

Charles

[JAWChemist]

Here is the link to the PDF document:

 

https://www.google.com/url?sa=t&source=web&rct=j&url=https://epub.ub.uni-muenchen.de/75968/1/prep.202000114.pdf&ved=2ahUKEwixm8CMxJ38AhXpqXIEHWvPAfUQFnoECCIQAQ&usg=AOvVaw3Kq6WpUZiPoZtUBsPuPbek

 

Charles

Thank you for your time and the link to Juknelevicius, et. al. "An Experimental Comparison of Selected Blue Flame Pyrotechnics". My request was more directed at kingkama for a link as I was having difficulty finding what he was referencing in his Post 12/28/22 5:20 PM.

[JAWChemist]

Hi Crazy Swede

The APC forum in Discord chat email alerts me. I have turned on "Follow this topic" so I am less likely to miss comments.

 

There are several topics but I'll save some of them till later after the holidays.

 

Item 1.

This is interesting and goes to the reason for joining the forum. My background is a formulator for metalworking fluids where I have both the expertise in the science of designing experimental mixture blends (DoE of Mixtures) and formulation chemistry of the component. For pyrotechnics, collaboration with someone that is less lacking in practical experience would be beneficial. Part of the delay in remembering to look for a reply was that I am converting a computer program written several decades ago to calculate blend mixtures for selection. It was limited by the total number of blends it could handle and that has had me sidetracked.

 

Item 2 and chlorinated rubber

What is your experience/opinion (safety/usefulness/stability) on using ammonium chloride in a formulation as a chlorine donor?

I have familiarity with chlorinated paraffins as they are used in metalworking. Using them as chlorine donors bring up the issues that these are used in compounding firemen's boots, don't burn well, leave a hard char when doing a flash point (they don't have one) that would necessitate a higher temperature which is bad (decomposed CuCl) and carbon tetrachloride (a low molecular weight analog) was used to in fire extinguishers. To release the chlorine, the material would have to be oxidized and chlorine should win over oxygen or the material has to be vapor ionized and CuCl destroyed. The discussion of chlorinated organic would suggest them as poor sources for HCl.

Chlorine would be available if the metals (Mg,Al) are used and make refractory oxides but then you have a high temperature and incandescent particles to wash out the blue light.

Considering the inorganic alternates used (mercury chloride and lead chloride) are acidic salts and would make HCl available to copper to make copper chloride. The most ridiculous extreme would be arsenic chloride but it has the issues of toxicity, being a liquid (frowned upon by regulations) and reacts with water. It is only mentioned as an example of how inorganic would make a great source of HCl like other inorganic chlorides.

Ammonium chloride would be a source for HCl but what I have seen suggest there are some stability issues with this (reacts with nitrates to make a slightly hydroscopic ammonium nitrate, tend to vaporize before being usable). One would expect ammonium perchlorate, which is used a lot, to have similar acidic issues as ammonium chloride. The nitrate can be an explosive. My only professional pyrotechnic works was on an inverter emulsifier to make a blasting emulsion. The ammonium chlorate seems to be far too unstable either as a component or occurring due to any instability reactions. It as used in the 18th century but replace by safer one. If this was due to the use of chlorate, it might be reconsider. It is also slightly hydroscopic. Most of the formulas give in https://pyrodata.com/chemicals/Ammonium-chloride all seem to have chlorate. https://www.skylighter.com/blogs/fireworks-information/chlorine-donor-chemicals notes its use but suggest it vaporizes out too easily.

I am looking at other chlorine donors. The current design has ammonium chloride as 1 of the 20 some components in it and the number has to be decreased because of excess computation time.

 

Item Hardt Blue #6

This is high in sulfur and uses potassium perchlorate. Sulfur (acid forming) seems to be an issue with chlorates. Is the stability issue with perchlorate and sulfur that much better? Do you have any information on the same formula with ammonium perchlorate other than thePihko BSP #4?

 

Mark Twin, “Sorry for the long letter but I don’t have time to write you a short one.”

Hi Arthur

Since you mentioned the emission spectra, one for copper chloride is available in the open literature. Formulas based on copper acetoarsenate (Paris Green) are often mentioned as a reference for blue color but I have not been able to find an emission spectra. Have you ever seen one? It is of interest because some of the formulas with this do not seem to contain a chlorine donor and it would be of interest to compare them for directional ideas. The alternative is to go research the local university library for reference not in the open literature.

 

Crazy Swede

Thank you for responding to the sulfur question. I must correct some initial comments in Item 2 paragraph 1. I was focused on ammonium chloride and other materials that would release HCl. For the mercury chloride and lead chloride, that should have been phrased using chlorine not HCl.

 

Arthur

The second about older copper acetoarsenate formulas not containing chlorine donors would have been better stated as “additional” chlorine donors beyond the chlorates.

[Crazy Swede]

@JAWChemist, this is what Kingkarma was referring to:

https://en.m.wikipedia.org/wiki/Flame_test#/media/File%3AFlammenf%C3%A4rbungAs.jpg

 

I have a hard time believing that is part of the explanation why Paris green compositions is considered good. Everyone who has used them says the colour is not that different but there is no red tip of the flame and most importantly, the flame envelope is very large!

[Arthur]

I don't know anyone currently using any Paris Green formula. Popular opinion seems to be that they make good blues BUT based on what? and when?

 

Does anyone currently use Paris Green? Has anyone ever fired Paris green side by side with any other blue comps? When Paris green was the first effective blue comp of course it was notable, the best in a field of one.

[Crazy Swede]

It would of course be against the law in most countries to release arsenic into the environment but as we all know, many hobbyists do as they please and in some states in the US it seems like you could do anything on your own property.

 

So, there is recent experience of Paris green blue stars and the consensus seem to be that they give a nice clean blue colour of somewhat higher light intensity compared to more modern formulas. They also ignite very easily and have a good critical wind velocity.

Edited December 29, 2022 by Crazy Swede

[cmjlab]

There are a few people who are licensed manafacturers with a dwindling supply of Paris Green who are using it currently. At least one is a well respected pyrotechnician amongst the U.S. pyro hobby community and a senior member of the PGI. I've not done a side by side comparison, but most people who've been around long enough to have experienced those formulations when they were commonly available, have stated they prefer the brighter / cleaner blue you can achieve vs. modern economically friendly Perchlorate formulas. The exception being they also seem to think Hardt's Sulfur Blue is a very close alternative, it just isn't as bright.

 

You are correct Arthur, a "good blue" is subjective, and even if you presented two formulas side by side claiming that one was better than the other, I could argue all day long that there is no "empirical scientific evidence" to support that. In the absence of such evidence, I'm left to make assumptions and form opinions on what I'd like to try, based on the opinions of other respected "old timers". For what it's worth, I'd also like to try the blue strobe formulations made from Guanidine Nitrate, as that is what is obtainable to me, but even those have been touted as the "best so far" but not the greatest blue there ever was.

 

As for illegal release of a toxic chemical, I can't speak to that, though I've seen a few substances banned for agricultural use being sold through chemical retailers in small amounts, that I don't imagine COULD be openly listed, or sold online in the U.S. if they were outright illegal. But I'm not lawyer or a cop, so I would have to concede to someone with more knowledge on that matter.

[cmjlab]

Actually, I believe there is concern with Potassium Perchlorate contaminating water supplies, and it's persistent presence in residential water supplies, that is the latest environmental concern.

[dave321]

if you have the right equipment, the brightness , hue and saturation can all be measured quite easily for comparison,

 

some work has been done i believe on blue strobes.

 

it is all reported in the scientific literature, but some materials like trimethyl ammonium bromide (if i remember correctly)

are a bit hard to come by if you are not in a scientific establishment.

[cmjlab]

Dave - my point is only that subjectivity remains with or without technical equipment. The subjectivity I refer to is the variations between how different people perceive the color spectrum, and that human eyesight is still able to detect subtle differences / changes in light but that is also different from one person to the next. I believe this is also alluded to in the study referenced above ( i.e. instead of equipment the author and his colleagues observed and reported their observations)

 

Additionally, I believe that emotional response to how we observe the color spectrum likely adds further subjectivity. I believe I read about that in F.A.S.T. and maybe Hardt too (not sure about that one though).

 

That was all I meant by "empirical scientific evidence" and subjectivity.

[cmjlab]

Before I get off my box.... This blue is most pleasing to me for a number of reasons, and is the best of all the blue formulas I've tried except Blesser's AP/Copper Benzoate.

 

The blue (Agten Blue / KCL03 based with 50% of the copper oxide swapped for copper oxychloride) has no metal in it, yet to my eye appears to match or overpower the Spanish Green with plenty of Mg/Al in it. I could never get Hardt's Sulfur Blue to match the brightness of the Spanish color formulas, and I have plenty of HCB to stick with the original formula.

 

video:https://youtu.be/aNmZVqYE0EE autoplay:0]

[kingkama]

Could you copy the link and post It?

As requested

https://en.m.wikipedia.org/wiki/Flame_test

[JAWChemist]

Thanks for the links.

 

On re-reviewing the info in the Wikipedia flame tests, I had missed the used of chlorides for my entire chemistry career for flame tests. Flame tests were little used in labs I worked in and it seems to suggest that any test might have to be prepped for testing. Later flame tests were briefly used to detect boron in metalworking fluids, which required prepping the sample. So, I found it a benefit to re-read.

 

I was attempting to find something related to flame testing associated with the other comments by kingkama (define the flame color as Paris green, using Cu carbonate/oxide in the same composition, testing organic fluids in the 1800’s for arsenic indigo color, the sum of 2 spectra, absorbing oxygen to lower the flame temperature or more used to make magenta) and scanned through the Wikipedia flame test link looking for a reference to one or more of the other items so I though there was other sites with more information.

 

Posts in the APC Forum chat on Discord are not getting to my email service to alert me. A similar issue may happen with this forum

[JAWChemist]

Sorry for cluttering up this thread but I forgot this question.

 

Combining potassium perchlorate with sulfur gives less problems with stability, compared to potassium chlorate, but you still have a rather friction sensitive composition. That said, potassium chlorate can be used with sulfur if the latter is non acidic but then you are playing at a much higher risk level. Personally, I would not do it without adding some kind of pH buffer, like MgO or a suitable carbonate!

 

Sulfur is a great fuel since it scavenges the potassium and therefore sets chlorine free that otherwise would have been lost as KCl.

 

Maybe, and just maybe, arsenic has the same effect by combining into potassium arsenide or arsenite, in paris green based compositions, and therefore providing the copper with chlorine even though there is no other chlorine donor than potassium chlorate. This is just my own hypothesis!

Hi Crazy Swede,

 

I have been collecting my thoughts in outline form. Unfortunately, there are about 4 pages. Some are ludicrous ideas (perxenate) and others not so much.

 

Here is a short list to peak your interest:

Juknelevicius results were analyzed by a stepwise multiple linear regression (MLR). It is not a rigorous approach as the test samples were limited in number and the materials were group based on my chemical bias. Interestingly the Pe (purity emission) was correlated with higher copper content. Not a big surprise but showed the analysis might have some moderate value. What was more interesting was that the H + C fuel had a negative impact on the purity. It was speculated that the fuel was presenting conditions to make the interfering CuOH. This data analysis was done after the speculation of the role of Paris green had been developed (partially discussed below) and also after a problem statement had been done where minimizing CuOH had been included. Of note was that the HC fuel was also found to be detrimental for 4 of the six results (CIEx color index, CIEy color index, Pe, and DWdif but not Burn Rate and Lsp ). DWdif is the Euclidean distance between DW (dominate wavelength) in Juknelevicius's paper and 470 nm. This had to be converted as DW bracketed the desired optimum while the others were to one side of a desired value and the MLR coefficients for these could be more easily interpreted as helping or hurting the value. It basically means minimize binder or use less H containing binders (H not there can’t make CuOH) and if you add fuels (metals were a separate class) then perhaps a formula based on C or S as opposed to stearic acid or paraffin would be better. I believe this parallels the Hardt Blue Star #6 and possibly the reason for your liking of it.

The Specific Luminous Intensity (Lsp) was interesting in being related to a sub-grouping of the chlorine donors and the metal fuel. While light output is important, if it ain’t blue it ain’t. Perhaps a better measure might be something like BLsp/Lsp%. This regression, however, does show the Achilles’ heel of the analysis as there is only 1 formula with metal.

 

For the emission spectrum, copper acetoarsinate may not be about what it emits but what it removes. If arsenite scavengers OH radicals and suppresses CuOH formation and thereby reduces interference, this loss would may not be seen in the spectrums given by Juknelevicius. The Paris green formulation had additional Cl donors that may have masked the originally reason for the use of Paris green in earlier historical formulations with no “additional” Cl donors. An alternate is that it has no affect on the spectrum at all and is simply a vehicle to get Cu (it has a lot of Cu) volatile especially since it present no water to cool the volatilization and should be more easily volatilized than the inorganic forms of Cu.

 

I am still looking into information on whether anything useful analog to CuArsenite from the Paris green can be found or has been tested like Cu stannate, … (there is a number of them). Like the simple chlorides one would expect them to have been examined but it did take 47 years after the discovery of HgCl by Chertier for Tessier to discover PbCl2.

 

There are a couple of materials that may be fairly viable alternates for the current Cu and/or chlorine materials.

 

Well I’ve Mark Twained it again. As a former colleague Dr. C. told me, “If you think it worth doing, you think its worth over doing.”

[kingkama]

Thanks for the links.

 

I was attempting to find something related to flame testing associated with the other comments by kingkama (define the flame color as Paris green, using Cu carbonate/oxide in the same composition, testing organic fluids in the 1800s for arsenic indigo color, the sum of 2 spectra, absorbing oxygen to lower the flame temperature or more used to make magenta) and scanned through the Wikipedia flame test link looking for a reference to one or more of the other items so I though there was other sites with more information

 

The informations they are not only on Wikipedia, they are taken from documentaries and read information on various writings Of pyrotechnics and not, but also personal experience and discussion with other professionals in the sector. However, it seems to me that this post is becoming a bit of a research on the length and color of the horn of unicorns and the reasons why this is the case.