particle size

[marks265]

From what I understand the finer the compositon particles are the faster they will burn. But a thought I'm having issues with is how does particle size relate with things like chlorine donors and alike to maximize color. If all components of a composition were pulverized to their smallest would color be the best? Or would you acheive the same results with less work if all were the same size but larger lets say 20 micron or even mesh, considering you could get them to ignite of course? I guess it just kills me when you want to buy a chem. or alloy and the first question is how pure is it but then what size do ya want!

[brok3n]

I don't know the science behind it, but most formulae call for the chlorine donors/resins to be around 200 mesh.

[mormanman]

I think that, if it answers your question (I didn't really understand it), is that the small it is the easier it is to heat up and burn. So then with a smaller partical size burns more and emits a better color. That part was about alloys and metals.

 

Oxiders I think is kind of the same principle only it can emit the oxygen faster.

 

I'm not real sure its just a guess like alot of what I say to stuff like this.

[Frozentech]

From what I understand the finer the compositon particles are the faster they will burn. But a thought I'm having issues with is how does particle size relate with things like chlorine donors and alike to maximize color. If all components of a composition were pulverized to their smallest would color be the best? Or would you acheive the same results with less work if all were the same size but larger lets say 20 micron or even mesh, considering you could get them to ignite of course? I guess it just kills me when you want to buy a chem. or alloy and the first question is how pure is it but then what size do ya want!

Well, for chlorine donors, oxidizers, binders, and *most* fuels, I feel that the goal is to get as homogeneous and intimate of a mix as possible, for smooth burning, easy lighting, etc.

 

I just went entirely through Hardt's Pyrotechnics and only found a single reference to mesh requirements other than for metal fuels and charcoal. One military flare comp called for 42-62 mesh Sodium Nitrate, 60 micron NaNO3, and 5 micron NaNO3, and the comp was "tamp-cast" by automatic machinery ( sounds a lot like ramming to me ). As for buying chems, get what you can, and mill it down fine as needed, except for metals and specific sizes of charcoal, which are needed for particular effects.

 

"Better is the enemy of good." - Voltaire

"Better is the enemy of good enough." - Sergey Gorshkov

[marks265]

I'm with ya frozentech. But something I was aiming at was to slow down a reaction and doing so with larger particle size if possible. I am wondering what happens to the quality of the color with larger particles.

I think it would degrade because it is less intimate as you have mentioned but yet still homgenous for a specific particle size.

 

bigger particles+cheaper material=more headaches( my new equation)

 

But yet another experiment is added to the list!

[Mumbles]

Color does degrade with larger particle size, but it really isn't too big of an issue. Red gum specifically I have heard about. If you take commercial standard Red Gum and run it through a 100 mesh screen, you will probably be suprised at how much stays on the screen. I have heard of several people screening their Red Gum before use and reporting better cleaner colors.

 

Generally if you want to slow down a reaction, you should drop the amount of oxidiser, and possibly replace it with charcoal or chlorine donor. Additionally I have seen that replacing Parlon for PVC or especially saran, will slow down the composition a bit.

[marks265]

I thought of reducing the oxidizer. I was thinking that throws off the balance at a molecular level and really mess up the color. I will certainly try your replacement suggetions.

I always screen my red gum and do so first because of that reason. Then I follow with other adds to clean the screen. But I sure like that smell!

 

Thanks for the ideas mumbles

[Mumbles]

It's possible it will degrade the color a bit. Increasing the amount of colorant probably can't hurt the color much. If you have a red with 10% SrCO3, perhaps 15% will do the trick. There is a fine line between slow burn and "dirty" burn. By dirty I mean slaggy and inefficient and such.

 

Just a little trick I picked up. If you want really slow stars, for micro stars, gerbs, etc try using colored gerb or lance compositions. They generally have excellent color saturation, and will burn remarkably slow.