Star priming

[Swede]

I am interested in hearing members' techniques for priming stars that are already dried. I had a large batch of a Winokur glitter that I thought would not need prime, but I was wrong.

 

I tried a light spraying with water, then rolling in a bit of BP prime (about 3FG; these are small stars) but the BP did not stick well at all. I then tried rolling them in thinned NC lacquer, followed by the prime, and this worked well but was quite messy.

 

Is it possible to mix up a spray-bottle with water + SGRS or dextrin, spray with that, then add the prime? Any other tips on priming rock-hard, dried stars? As always, TY all.

[Ventsi]

I would suspect the graphite used to glase the BP prevents it from sticking.

 

I usually mist them with with water/Alc. and roll them with milling dust for a bit and thats about it.

You could put some dextrin in the water/alc and roll them in some FFF or FFFF{no G's}.The soft meal powder prime should let them stick right to the stars.

Edited May 22, 2009 by Ventsi

[Pretty green flame]

I make a thin slurry of priming composition and wet them with this slurry, then 2-3 coats of dry prime, works good and provides a good connection between the prime and the star. A star roller makes the job so much easier, if you don't have a roller, then a large bowl works good too. I noticed that when i was spraying them with pure water the prime would over time chip off. The above method is pretty much fool proof and gives good results.

[Arthur]

What was the original binder?

 

Dextrin softens with water, SGRS is supposed not to soften once hard dry. Acetone or alcohol will usually soften whatever they bound.

 

I have a mix of 75/10/10/5 meal powder the 5 being Dextrin add a teaspoonful of hot water and a desert spoonful of powder goes very gluey and sticks well when dry. Add some powdered silicln for a nice slaggy flame for better ignition transfer.

[Swede]

Is it best to wet the stars, the prime, or both? These stars had dextrin, IIRC. I might have been a bit timid with the water when I tried spraying them, and then the addition of the dry prime failed. The NC kicked ass but was a mess and impractical, unless you need stars primed and dry in 30 minutes.

 

I know Si helps, but unfortunately I don't have any. I'm thinking coarse Al might help, but most of the stars I make are not hard to light, and are easily primed with BP.

 

I'll try an experiment creating a slurry of coarse BP, dextrin, and then rolling that onto the dry stars and see how well it adheres. One other trick might be NC lacquer exceptionally thinned, and then sprayed with an airbrush or touch-up paint gun for larger batches; immediately roll in dry prime.

 

I don't know why I failed to prime these when they were soft and damp. Thanks.

Edited May 22, 2009 by Swede

[Yankie]

I always let my stars dry before priming, I just always have the fear that they will crumble when trying to prime them. I put them on a mesh screen and spray with water/alc from both sides, give them a little shake every now and then. then once they are fairly wet dump them in a container 1/4 full of prime, put the lid on, and roll the container about in my hands. After a minute or so of rolling pour the stars onto some mesh to seperate the excess prime. The stars are then dried and ready to go. For harder to light compositions that need a step prime I do the same thing, just twice.

[psyco_1322]

The type of star usually determines whether or not I let them dry before priming. If they are charcoal streamers of some sort, and are prone to be driven in, I will let them dry completely before throwing them back in to wet down and prime. If they are some sort of low charcoal glitter or colored comp, I usually just roll the prime on right after I roll the stars. I don't want my outer prime layer to dry up and leave a moisture proof barrier keeping the charcoal stars from drying. This usually happen if you prime with a straight mill dust prime.

 

I have been priming most of my stars with my personal formula. It's not sacred or special, so I'll share it.

SI Prime

KNO3 - 20

Airfloat Charcoal - 5

Sulfur - 5

DE - 1.5

Dextrin - 2

 

Just hand mixed, not milled or anything. The nitrate is of coffee grinder fineness, not an airfloat consistency. The DE makes for a fuzzy type of prime, kind of like wood meal. I suppose wood meal could be substituted if you have no DE, but it's cheap and you don't use a lot. Wood meal is just fine sawdust, such as what you would find building up in your belt or orbital sanders. BTW, the SI is my initials and has nothing to do with elemental silicon that some use in primes.

[Mumbles]

I pretty much always wait until my stars are dry. I generally cut or pump everything anyway. I give them a pretty liberal dousing with water. Until the outside starts to shine, and the stars barely begin to stick together. This may seem kind of backwards, but I want to make sure my prime is well adhered. After this I sprinkle on prime by the handful. Usually green meal with some atomized Al or MgAl in it. I have a "prime bucket". I let all my stars dry on screens, and anything that falls through gets added back to the prime bucket. This adds some coarseness to the prime. There are bits of stars and crumbs in there too.

 

If I have a hard to light star I apply the Veline Style Super Prime, and then green meal over the top of that. I've been meaning to try those fence post or pinball primes. Ideally I wouldn't have to use the veline style prime, as it's a little complicated for it's application.

[Swede]

Good stuff, and some great ideas. I like the "prime bucket" concept, with a screen over the top.

 

I've mentioned this before - some craft stores have pecan shell flour which is a good substitute for wood dust. It's cheap, and they use it to make resin look like wood once poured into a mold.

[swervedriver]

Anyone tried spray starch? Spray the dry stars with aerosol spray starch, then roll around in the prime?

[Arthur]

I'd be cautious about the "prime bucket" it's one way to make a very complicated chemical soup with an ever growing risk of inconpatibilities.

[Piet]

Priming is always a pain in the butt.

 

Maybe this is useful info on NC-lacquer.

I am using an old hair-gel spray container from my wife, To my surprise it withstands the acetone very well and no evaporation on shelf, even after 3 weeks.

Shake the bottle and its ready to use.

 

My results on Pingpong Balls/acetone comes with a mixed feeling however. In the picture i am coating AP/Hexamine blue stars, when ik spray them afterwards with water the stars look really watertight. Even after 5 minutes the water is still clear of any contamination. Butt when i dip my nc-coated bridgeless ignition wires into the water the resistance measured with an Ohm meter immediately goes from 5 to > 70 Ohms and still rising, even when i pull it out of the water. So my guess is that i have to find real pure NC-lacquer. (my pingpong balls looks to be the right ones, they smell like cellulose and dissolve perfect in acetone)

 

Another remark on wood meal, i used 5% 120 mesh to the prime but it left a lot off sparks during the break of the shell(short lived) in a peony shell undesirable.

 

Here is the shell where the priming failed and also left some sparks from the wood meal:

 

http://www.pyrobin.com/files/3r%20ap-hexamine%20blue.mpg

Edited May 24, 2009 by Piet

[Mumbles]

Well, it should be common sense not to use AP or chlorates in the mix. On the rare occasion I do use them, I have to use special primes anyway. Other than that, everything I use is compatible with the others.

[Piet]

Well, it should be common sense not to use AP or chlorates in the mix. On the rare occasion I do use them, I have to use special primes anyway. Other than that, everything I use is compatible with the others.

 

General consensus is that the best blue (and some other colors) comes with AP. to the best of my knowledge is that coating with NC-lacquer is sufficient to isolate the AP.

Next in line is Bleser prime followed by meal.

My AP-hexamine star (parlon and copperIIoxide) instead of regular CuO and saran) was a big disappointment to me. I am only looking for the best and brightest blue there is.

 

If you can give me a other compatible prime, please share.

[Mumbles]

The problem is that best blue and brightest blue are generally not one and the same. Good brightness unfortunately often comes as the cost of color saturation. I have 2 formulas I use, one bright, one good colored. Neither of which utilize AP. I can get quite excellent color without having to result to AP or chlorates.