Pearl, Tremolante and Twinkler

[AdmiralDonSnider]

It is Lloyd Scott Oglesby who sketches the possibility of tuning glitters by the means of charcoal in "Glitter, Chemistry and Techniques" p. 59f. Herein he talks about ball milled glitters (all chemicals ball milled except the aluminum and the charcoal) and says that when:

 

"using air float charcoal and 80 mesh charcoal, we observe a steady progression of the expected changes in effect. Larger differences in spritzel diameter cause larger differences in exposed surface-to-mass to be air oxidized. This larger time difference before the spritz explosive can be formed causes larger differences in delay. Now when the stars are shot from the comet tubes, the long tail associated with the glitter (called tremolante) begins to form with the air float charcoal and is more fully developed with the 80 mesh and below charcoal. Naturally, there is a point of diminishing returns for the trick of using more widely varied charcoal particle size. At eight mesh, the glitter of most mixings is destroyed. 16 to 20 mesh and below are used for twinklers (very long tailed glitter effects)."

 

These lines explain how controlled variations in the particle size of the charcoal can be used to critically change the appearance of the glitter stars. They basically say that every common glitter, e.g. D1 or Winokurs (common glitters show a "pearl", that is a rather short tailed, appearance by default) can be given the long-tailed appearance of a "twinkler" by means of adding coarse charcoal.

 

I guess such an addition has to be well balanced if the effect should succeed. Where are the APC experts, who can point out some tricks to tune one´s glitters?

Edited August 10, 2009 by AdmiralDonSnider

[Mumbles]

I find this is more useful in comets than stars. Unless you're making large shells, I found that it caused too much fall out if you're not careful.

 

It really means that any coarse material can act as a nucleation site for larger (longer hangtime) spritzels. If you use unmilled KNO3, you will get a nice long delay as well, as I have found out far too many times. If you've ever seen Win39J, you can observe this effect as well. It has a few parts (2.5%) of -60 mesh MgAl. It both changes the glitter, as well as providing additional glittering effects from the MgAl. This is the kind of additions I prefer, and doesn't seem to cause the same fall out issues. Perhaps it is because it reacts with the spritzel. I've heard of coarse Al, MgAl, and C all being used for this effect. I bet Ti would be interesting. It might provide a unique multi-toned shimmering effect.

 

I'd start with 2-3 parts additional coarser material as a beginning point. My reasoning behind this is that it provides a slight control. You are not changing the base formula, simply providing additions. This is in contrast to replacing 2-3 parts of the charcoal or Al with a coarser material. It also allows easier testing. You can make up a large batch of base mix, and use various additions to do a spectrum of tests at once.

 

It's interesting that Oglesby mentions milling without the charcoal or Al. I'd also leave out Sb2S3, but that is just to preserve the mesh and material shape. I never noticed this before. I'm a big proponent of not milling glitters for a better effect. I see too many short lived glitters. I bet just milling the KNO3, sulfur, binder and carbonate/oxide would prevent this, and ensure all the chemicals are fine. I may try a few test batches.

 

Other modifications I've used:

 

Increase the delay agent - If using bicarbonate, you can encounter fall out. If using barium carbonate or some others, I find it simply increases delay without making it too much drossier. I noticed that it seems to make fewer, but larger flashes. If using Sb2S3, it can change the effect in a different way. It seems to increase the delay, without reducing the number of flashes. This is personal experience, others may disagree. I took this to mean that the carbonates contribute to the liquid dross volume, while Sb2S3 seems to thicken it up or somehow retard the reaction, without changing the volume very much. That is a thought experiment I did, but is really not backed up by anything.

 

Change the delay agent - SrCO3. That's it. It really lengthens the delay. This is a proven concept on many occasions. You can replace part to all of the carbonate to help to delay it. I find that alone it tends to look slightly pink. Barium turns it bright white though. So, in short, either use this trick with glitters containing a portion of barium nitrate, or use maybe 1/2 to 1% barium carbonate overall in the composition.

 

You can use a coarser Al. This goes along with what was said earlier. Most of the original glitters were made with Alcoa 120. This has a mesh of roughly -120+325. I think it makes a nicer glitter. It has a longer tail.

[Twotails]

Wow, Im glad i came across this forum. I always use Lampblack for nice dense trailing dim-gold sparks. I've use star formulas with Ferrotitanium, sparkler grade steel powder, magnisum, and aluminum, and mixtures of the above. but i always go back to useing lampblack. Another good charcoal is hemp charcoal ( found a few wild plants, cut them down, and chard them, next time i'll try useing hemp string). I also found somthing interesting, one night when pressing stars, i got inquisitive, and found that pure citric acid can liquify and will catch a flame. so i tried useing a little in just a simple BP star. I cant explane it, but it just seemed that the shell filled with those stars looked better then the other. I'll have to try it in the next comet i press. i used about six grams ( im unsure, becouse made the mistake of not mesureing it, nor writing it down) of powderd citric acid to about 100g of composition, simple 75/15/10 BP.

[flying fish]

Welcome to the forum!

 

However, this thread is about tuning traditional glitter effects based on charcoal variations. You might want to post your story somewhere in the random section (like in the random thread or introductions), or perhaps start a new thread under "pyrotechnics". You can also share compositions in the "compositions" section if you feel so inclined. I'm interested in learning more about lampblack effects myself...but I don't think this is the place to discuss it...

 

Well, one way to tie it into the discussion...has anyone ever tried substituting lampblack for charcoal in glitters? I've intended to try this, but never got around to it.

Edited August 11, 2009 by flying fish

[AdmiralDonSnider]

It really means that any coarse material can act as a nucleation site for larger (longer hangtime) spritzels. If you use unmilled KNO3, you will get a nice long delay as well, as I have found out far too many times. If you've ever seen Win39J, you can observe this effect as well. It has a few parts (2.5%) of -60 mesh MgAl. It both changes the glitter, as well as providing additional glittering effects from the MgAl. This is the kind of additions I prefer, and doesn't seem to cause the same fall out issues. Perhaps it is because it reacts with the spritzel. I've heard of coarse Al, MgAl, and C all being used for this effect. I bet Ti would be interesting. It might provide a unique multi-toned shimmering effect.

 

I'd start with 2-3 parts additional coarser material as a beginning point. (...)

 

That´s some very useful information, Mumbles. Thanks a lot.

 

It´s just very interesting that there are close to none formulations that include such coarse material (to lenghten the delays) by default. The standard is airfloat or -80 mesh charcoal and about 300 mesh atomized Al. If you mention Win39J, I guess you refer to the formula given by Tom Rebenklau in his Crossette Rocket Video. Seems to be the only formula which includes coarse metals.

 

You´re right about the principal technique, which makes use of coarse materials to retard the spritzel separation from the stars. In addition to the charcoal, Oglesby rates coarse aluminum (flitter) very high for this purpose. I´ll give it a try and will add your suggested 3% as soon as I got my flitter.

 

Other very promising techniques - according to Oglesby p. 64f - are ricing and wet blending of glitter mixes and the author uses them to combine diverse properties of different glitters in one star e.g. to make a white or pink headed comet with a yellow twinkler tail. Any experiences in this area?

[andyboy]

Please excuse this if firefly is deemed to be a different subject than the OP's glitter tuning.

 

 

I think it's perfectly on topic since the topic is pyrotechnics.

 

Good info there but I would love to get some info on the mix made by Flower City charcoal Co, anyone?

[AdmiralDonSnider]

There´s another question linked to the glitter effect which came to my mind:

 

If to use charcoals designed to give the best spark or charcoals designed to provide force? The main thing is that most people (including myself) seem to use the same charcoal they would use for charcoal streamers for glitter stars, e.g. pine or beech or even plain hardwood airfloat; charcoals said or proven to give good spark effects.

 

But when I read Oglesby I get the impression that good and fierce glitters rely on high performance charcoals such as willow, hemp, paulownia, alder buckthorn etc., all of which giving a good amount of thrust to the spritzels and thus making a wide spread.

 

What do you think is best?

Edited August 11, 2009 by AdmiralDonSnider

[TheSidewinder]

Interesting reference to Flower City vs Flour City. And I wonder if there's an actual tie-in there somehow.

 

A bit of off-topic trivia:

 

Minneapolis, MN, was known world-wide as "Flour City" for a period of time in the 19th century, when we led the world in flour production.

 

Washburn, Crosby, and Pillbury were then the leading producers, and we made headlines whenever one of the flour mills blew up (as they were prone to do in those days).

 

The Washburn "A" Mill was the USA's largest mill at the time, and when it blew it took out several city blocks: http://www.mnhs.org/library/tips/history_t...73washburn.html (or google "Washburn A Mill explosion").

[TheSidewinder]

I assume you mean Rochester, NY. Genesee River was a tipoff.

 

(We have a Rochester in Minnesota, too, but it's home to the Mayo Clinic. They never made any flour. )