simple blue stars compositionii

[THEONE]

I am trying to make a simple blue composition. I have tried kclo3 6g, Cuo 1g, 2g erythritol. The composition burned more like greenish and the flame i could tell that it was mostly white. I added some dextrin to th comp to see it how it performs as a star. Any ideas why that is happening? Do chlorate donors like parlon will do the difference? I believe kclo3 got enough cl right ?

[NeighborJ]

The blue color spectrum displays best at low temperature. A stoichometric fuel value often burns too hot. Most blues use stearin, hexamine dicyandiamide or other high gas producing chems to drive the combustion temperature down.

 

Stearin would be one chem I'd add but an extra few percent of PVC or other chlorine donor usually improves the color.

[THEONE]

So do you believe the sugar creates too much heat for blue ?

[NeighborJ]

The carbon in the sugar molecule imparts a yellow color to the flame. Ideally you would want to use redgum, shellac, phenolic resin or similar fuels in place of the erythritol. From my experience sugars will also mold in storage, it's another good reason not to use them in pyrotechnic compositions.

[Arthur]

There are so many composition lists on the web, please find one or two and use established formulae that work. It's hard to start into the hobby and surpass the research done by Shimitzu and the Chinese and the Italians/Maltese and Spanish -even the Brits have a repository of knowledge and anecdotes in the books by Lancaster and A StH Brock

 

http://www.thegreenman.me.uk/pfp/db1.html has lists of formulae for many purposes.

[THEONE]

Can pine resin (colophony) be used instead of redgum, shellac, phenolic resin e.t.c. ?

[NeighborJ]

Colophony is listed in FAST as burning almost identical to shellac but it imparts a yellow flame.

 

It could make a passable blue but the cabon in it is difficult to overcome.

[THEONE]

I see, so i guess it would be ok for yellow-orange-red compositions but for blue-green shellac would be better.

[NeighborJ]

Yes, warm colors will be able to hide the carbon flames better. Shellac still has a slight yellow flame but it can be hidden enough to still make cooler colors. The best common fuel/binder for blue would be redgum, PVC, parlon, sulfur or hexamine, there are many others thou.

[Mumbles]

Lactose is the most common sugar fuel. I'd start with some formulas employing that and modify as you need. They tend to be cooler than most fuels, so you may be on the right track. If it's too yellow or green, you might just not have it balanced right.

[Yus]

KClO4 – 50%, CuO – 20%, PVC – 10%, S – 8%, AlMg – 5%, phenol resin or red gum or similar gum or resin – 7%.

[kaotch]

@Yus,

Thanks for posting this formula, what mesh size did you use for the MgAl?

[Yus]

fine, less than 0.08 mm, better less 0.04 mm.

[kaotch]

Thanks ,do you have a video?

[Yus]

Yes, rolled round stars, see 1:20.

 

https://youtu.be/-76Re7pIsQQ

[Arthur]

Good blues are hard, sometimes someone else's formula that works doesn't work for you, simply because of material purity issues. There was a good book by the Kosankes that went into lots of detail of the spectral emissions of various radicals of copper by-products in the flame and how to select a whole formulation that works well.

[Yus]

Arthur, I totally agree with you. Good blues are usually based on NH4ClO4, but for newbies it is better to start with simple one containing KClO4. It is better to see blue stars in the sky and make conclusion. And second, all of us have different sensitivity to color, one sees blue, another - violet. At video above you can see recorded of two cameras, thus the same blue stars at 0:32 and 1:20 look differently. Here is going videos of a few experiments with blue compositions.

 

https://youtu.be/odu16aJSXgc

 

https://youtu.be/J-BlkEtkPn8

Edited February 3, 2020 by Yus

[Arthur]

Copper has a whole selection of flame product radicals that emit most of a spectrum of light when hot, it's very definitely essential to pick a known good formula or experiment wisely. Only the copper chlorine flame products emit blue light. Flame chemistry doesn't follow any school rules! impossible molecules exist in a steady flow it's these that emit blue light, only by controlling the flame conditions can you get a good blue.

[kaotch]

Yus,

Thanks for posting the vid. At the moment I am trying out a blue formula based on KCLO4 without MgAl but with the addition of Lactose and can report that the result is looking very similar to your Blue.Unfortunately my vid is lost.As a matter of interest what kind of prime(s) are you using?

[Yus]

I am using chinese prime. Basically it consists of BP 100%, 15% KClO4, 10% AlMg (350 mesh) and 5-8% Phenol resin or mixture with dextrin (over 100%).