Green Stars, Hygroscopicity, and Particle Size

[pyrokid]

So I got tired of wasting copious amounts of magnalium and KClO4 on carbonate greens.

 

I purchased some BaNO3. My results, although they form a very limited sample size, have been very mediocre. The material came in clumpy, and the crystals were very large. I dried it and milled it. Some of these procedures were a bit hasty, but I ended up with a fair amount of "dry" powder. The star mixes I've tried just haven't been very good. I don't have my notes so I can't say the comps I tried.

 

Should I try harder? Are nitrate greens generally regarded as good?

 

 

Would switching to BaClO3 solve my troubles? If the nitrate has a low ceiling in terms of the quality of green it can produce, I don't want to waste time trying to perfect formulas, and I can find other uses for it.

 

I've seen a few examples, in video and in person of a fantastic, cool, vibrant, grass green. One was a video from malta, and the other was at a private shoot, so I feel like chlorates were involved.

 

 

Any help is appreciated! Are there any favorite formulas?

[mabuse00]

Hi

 

 

So I got tired of wasting copious amounts of magnalium and KClO4 on carbonate greens.

I agree. Works with red, but rather not with green.

 

 

The star mixes I've tried just haven't been very good

Can you elaborate that? Define not very good.

 

 

Are nitrate greens generally regarded as good?

Yes!

Actually you wont find anything better. As long as it's not somehow contaminated with some other metal ions, but this does not seem to be a common issue.

 

Try Hard Green No. 5:

 

Barium nitrate 56
Red gum 7
Magnalium -200 mesh 17
PVC 15
Dextrine 5

 

And if that burns to slow, google Kyle Kepley's Emerald Green.

 

Both have a reasonable pure colour with high brightness. And if not, there's something wrong.

 

 

 

Would switching to BaClO3 solve my troubles?

What are your troubles?

 

Typical organically fuelled Ba-Chlorate formulas gives a purer colour, but they are not very bright. When watched in total darkness they are very nice, but barely recognised when not alone in the sky.

A nice thing to play around with, but for practical pyro purposes nitrate is the way to go (imho).

[Maxim]

Here is a very good comp:

60% BaNO3

20% magnalium

15% PVC

5% Dex

+5 Iditol ( phenolic resin )

Use vodka to make the star comp wet. Very good for star-rolling, but if you are making them cylindrical you should press them a bit, also very good for knife-cutting.

 

And another one:

60% BaNO3

20% Magnalium

20% PVC

+ 5% Phenolic resin.

You can use vodka or pure alcohol to water the mix up. If you do not have a star-roller you should press them. Abount 90 kgs on the 8 to 8 cm squar.

 

Both comps make very bright green light. I recommend.

PS: if they burn a bit yellow try to lower the % of PVC or check the quality of BaNO3.

[AzoMittle]

My order of preference for color purity, and note I say my preference because unless you want to pull out the spectrometer, the adiabatic bomb calorimeter, and the other fancy toys we -are- talking just in preferences and not hard numbers, is:

 

Chlorates --> Nitrates --> Carbonates

 

My order of preference for safety and ease of use (aka the real world) is:

 

Nitrates --> Carbonates --> Chlorates

 

However, any of these can give a great or a crappy color, it depends on a lot of things. For example, you may be able to make a color that is beautiful on the ground but will blow blind 100% of the time in the sky. I use nitrates 99.999% of the time, like mabuse00 said they are simply practical. I like carbonates if I want a more bright pastel color or I simply want to do it cheap. I won't bother with chlorates unless I have a good specific reason.

 

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The absolute most pure green you are going to be able to get is from 90% barium chlorate 10% shellac. HOWEVER! IIRC this was originally a lance formula and not intended for stars (though I have used it for such successfully). Despite the purity I find that it is not worth dealing with the chlorates, too many incompatibilities (especially dealing with primes and burst and so on, not to mention having to clean your tools all the time) and safety issues (friction and impact sensitivity). I find that a well designed nitrate formula isn't far behind a chlorate, though noticeable side by side.

 

Oh, and remember, you don't have to limit yourself to a single color producer (though it is a good idea to begin with a single one). Try swapping out 10% of the Barium Nitrate for Barium Carbonate, see what happens.

 

You mentioned that you are looking for a "grass green", I would look at the Spanish Lime Green and Spanish Green #2 formula and the Hardt green. Could you link us to these videos you mention so we can understand better?

 

Spanish Lime Green #2

• 24 BaNO3
• 18 KClO4
• 15 MgAl (230 Mesh)
• 12 Parlon
• 11 Ba Carbonate
• 09 Red Gum
• 04 Dextrin
• 02 Cryolite OR Na Oxalate

 

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I feel that in light of several recent threads I should mention that a lack of color purity is not necessarily a bad thing, it can be very very good in fact. We need contrast in the sky. A deep dark pure colored shell fired next to/before/after a bright impure pastel color will look even better. When everything is a high point, nothing is. It needs an ebb and flow, not just all go all the time.

[pyrokid]

Update:

 

I tested one formula. I tried to make some crossettes with my tooling and Jopetes' second green formula:

 

KClO4 - 18

BaNO3 - 45

Red Gum - 10

Parlon - 9

MgAl - 14

Dextrin - 4

 

This was a nice green. Unfortunately, the crossette failed. More refinements are necessary. 7/3/1 flash is definitely powerful enough for 1/2" crossettes, as it blew the comet apart with a very loud report.

 

I suspect that the source of my problems was granular BaNO3. I blade milled it before mixing the composition this time and I was happy with the results. I've seen suggestions that the Shimizu organic comp that I tried originally tends toward yellow anyway.