What is this effect?

[isaak]

Can everbody say what is it for a effect?

Have anyone an Formulary of this Bean Effekt?

 

[nater]

I have seen that effect commercially labeled as "gum drops" or "jelly bean". I am not sure what the actual term would be. We have talked about it before, I if I remember right the consensus was they are nitrocellulose based microstars.

[lloyd]

I don't know the names of other brands, Nate, but yes... they are NC-based. They're essentially just pressed pellets about 1/4" diameter by about 5/16" long filled into a paper tube. The ones I've seen had tubes about 1" i.d. NO propellant is used except for the gas generated by the burning of the NC, itself.

 

Lloyd

Edited January 5, 2016 by lloyd

[Shiffdaddy]

Hello everybody my name is Ben. I am a chemistry student and a lifelong pyromaniac . First of all I would like to apologize for posting on this thread but I was unable to make a new topic for discussion/saying hello. I've been particularly interested in the colored compounds of fireworks and have been making a few stars. I have been reading around for a few weeks now on the forums but never really thought about posting until now.

 

My particular question though is on the reasoning behind using magnalium over aluminum or magnesium. Is there a safety issue behind the chemistry of some of the compounds used with the metals alone that is bypassed when using magnalium? Or is it purely a visual appearance thing?

 

Ben

[lloyd]

Ben,

Magnesium is attractive because of its reactivity at fairly low temperatures, compared to aluminum. However, that's also its down-falling in terms of one's using it alone as a metal fuel. It's SO reactive that it will react with many oxidizers (notably potassium nitrate and/or BP) at room temperature, using only the ordinary waters of hydration and slight hygroscopicity of the mixtures. The reaction can be anything from a fairly rapid degradation of the effect until it no longer works, all the way to self-heating and possible ignition.

 

Magnesium also tends to make a relatively 'transparent' flame envelope compared to aluminum.

 

Aluminum is more stable, requiring less protection from reactions than does magnesium (but still, some protection). It burns bright-white hot, and makes a very opaque smoke, thus detracting from effects -- especially colors, which become 'washed out' from the broad spectrum contribution of the Al.

 

A 50/50 Mg/Al alloy ("magnalium") is less reactive than magnesium, and possesses some of the characteristics of both in compositions.

 

Magnalium also plays an important role in the "crackle phenomenon", where the magnesium is preferentially consumed until the mixture heats to the ingnition temperature of the oxidizer/aluminum mixture, which then explodes violently.

 

You'll find Mg/Al used in most metal-fueled color compositions.

 

Lloyd