BP Prime

[Swede]

It seems every tutorial I've read where priming of stars with BP is discussed, the usual advice is "Prime with meal." Sounds good, works fine. But my understanding of how flames propagate is this - corners and sharp irregularities in the surface promote easy ignition. Why then prime with meal, when a corned BP in FFG or FFFG will leave the star studded with BP granules that will easily ignite?

 

Is it because heavier granules of BP prime will be knocked loose by the burst, and not do their job?

[Bonny]

It might be more of an issue of getting the granules to stick. I have read instructions where a slurry of BP is used first and then the star/comet is dipped in granulated BP to give the crusty jagged surface.

In several videos from china, I've seen them prime rolled stars by pouring (BP?) slurry into the star roller.

I've also been considering making my primes into a slurry then rolling stars in it, rather than misting and sprinkling ,which takes forever and a lot of prime falls off.

Has anybody done much of this?

[Pretty green flame]

I've heard that adding 5 or so % of wood meal to the priming composition adds to a somewhat fuzzy finish, making the prime itself easier to ignite. IMO i'd rather use this than any ammount of high grade BP as a priming composition. What can you do, i'm stingy as hell.

[Mumbles]

Exactly. Meal is a raw(ish) product. The granular stuff is not. The problem is definitely getting it to stick. A slurry of BP is used for comets, and this provides enough sticking powder for a coarse grain powder. If I were going to try to roll granular powder on my stars, I'd go no coarser than meal D, which is -50 mesh.

 

Personally, I don't waste good meal on priming stars. Speed is not always good in primes. I always use green meal, just hand mixed components. It burns slower, so it gives a bit more flame exposure. It's cheaper and easier to prepare in larger amounts too. I also don't have to waste my good charcoal on it.

 

Other "fuzzy" things can work too. I remember seeing some diatomaceous earth being used before. Coarse metals or charcoal will also help.

[FrankRizzo]

The trouble is that most people think that "Meal" means the talcum consistency fine powder straight from the ball mill jar. This is incorrect. The powder you get straight out of the mill jar is properly called "mill dust". Meal D is the very fine granular material that's left over from the corning process, and is composed of very fine granules with a very large surface area and many ignition points. If you see a formula that references Meal as one of its components, substituting mill dust will make a slower burning composition than what the author intended.

[ULTRABUF]

The trouble is that most people think that "Meal" means the talcum consistency fine powder straight from the ball mill jar.

Thanks for clearing that up frankrizzo. If you don't feel like using up all the good fines from corning, would granulating some meal with a very fine screen be an acceptable replacement in formulas calling for meal?

[Mumbles]

I think you'd end up with a messy screen. It'd probably be easier to granulate through a window screen, and remill. It is the traditional way to make charcoal streamers and spider stars. It makes them burn pretty quick. It all depends on efficiency of the mill of course. I'd check every 15 min or so, and screen it through a fine screen every so often, re-milling what doesn't pass.

[Swede]

The trouble is that most people think that "Meal" means the talcum consistency fine powder...

Ahh, that explains much. I also thought meal was the stuff straight from the ball mill. The terminology behind BP can be confusing.

[Richtee]

Prime while pumping?

 

Pumped some 3/8" Hardt #1 today and had a small container of my BP wet with NC next to me. After filling the pump, I gave it a little more space and pressed into the wet BP. Seems easy enough..only thing is only one end gets the prime.

 

On Edit: PLEESE ignore the red stuff... it's just left over pizza sauce LOL!

 

http://i471.photobucket.com/albums/rr72/esalink/100_8213.jpg

Edited January 3, 2009 by Richtee

[TheSidewinder]

Now there's a touch of real Italian Pyro! Pizza Sauce!

[psyco_1322]

Makes them stars look tastey.

 

I have a prime that I use DE in. It does make the prime layer slightly fuzzy like wood meal does. I also always use just screen together chems for primes. I causes them to be a bit more drossy than a milled product, which is good for ignition. I recently bought some silicon, so I'll be switching over to using fence post prime soon.

 

I have a hand full of stars I got from Dan Creagan at the 07 convention which look as if they have a granulated bp prime. Its stuck on pretty good. Not sure how he goes about getting it on. I tryed it once with little success as most of the granules where rubbed off during handling. I also have some odd colored stars I got from someone that have a heavy prime layer that contains some kind of Al flake/flitters. Looks almost like that crappy firefly Al that resembles cut up foil, but this is thinner and smaller pieces.

[Ralph]

i always use a green mix which has airfloat willow which i mill for 1 hour with sulfur as my sulfur is in granuels and than staright kno3 crystals i than sometimes if the star is hard to ligh add some sheprical al powder that always works great

also if you are having a hard time lighting stars make cut stars they always light

[Mumbles]

I've had many experiences that will disprove the cut stars always light comment.

[TheSidewinder]

Umm, yeah. I can think of one example, too: My "time delay blue" stars.

 

Mumbles remember them. Gave a few WPAG members a good laugh, including me.

[Mumbles]

They lit, just after they hit the ground.

 

I went through a period when stars and I were having priming issues. It's responsible for 4 failures of my 1/6 record on double petal shells.