Sawdust or Coarse Charcoal Prime?

[LiamPyro]

My 4th of July show was a mixed bag. Rockets all flew great and the 8 oz made on Woody's Super BP tool even lifted a heavy (170g) 3" shell to good height. However, around half of all my stars blew blind! Priming was either Fencepost prime (+25% star weight) followed by airfloat BP meal (+15-25% star weight) or just the meal on streamers/glitters. My shells broke extremely hard, a little too hard, as they were pasted more throughly than usual but were still generously boosted (up to 6g slow flash or whistle in 3"). Looking at the footage frame by frame, I noticed that in some shells, there was no indication that the stars even lit in the first place (as opposed to the prime lighting and burning off but the stars not taking fire). This was even true among some of the charcoal based stars, especially rolled ones, leading me to believe that the prime layer was too smooth and therefore didn't light. My plan is to incorporate a thicker prime layer to ensure that it doesn't all burn up inside the shell and that the stars have a little time to slow down, but I'm also thinking that I need to incorporate something in the outer prime layer to help them take fire. I tried ricing, milling, and then rolling the meal prime to prevent raspberries and provide roughness, but this didn't work very well as the granules tended to smooth out with the rolling. Would adding 5% fine sawdust or 80 mesh charcoal accomplish this, as is used in Veline Superprime? Or simply switch to a scratch mix outer layer? I can see how scratch mix would provide the advantage of a rough surface and a slower burn thus giving more time for stars to slow down, as opposed to an equally thick layer of meal, but I like the idea of following it up with a thin layer of milled powder to ensure strong and complete ignition of the whole surface. Any thoughts? What are your solutions for rolled stars not lighting? I know this issue has been covered before to some extent, but I'm specifically concerned with the outer layer roughness as it affects star ignition - I know that simply adding more prime will solve any issues of them not staying lit.

[All10Fingers]

Sounds like you put more effort than I did... Mine were half blind too. Maybe try something that burns hotter. Like a metal. I usually just add a little dark aluminum to fine BP. Sometimes if the jar happens to be close by, I'll sprinkler a pinch of barium nitrate as well because I read somewhere it burns bright and hot with metal fueled stuff.

I'm definitely not the best person to take advice from as I myself am currently working thru prime problems. But that's what Ive been doing at least 

[Zumber]

Two prime stage works all well for me even if shell is bursted using just flash powder.

At first stage use slow burning prime that has high charcoal percentage and add 5  to 10 percent 200 mesh magnelium in it and 10 percent barium nitrate in it.

Second stage is just screened bp mixture that burns slower than milled bp.

[Arthur]

Prime is as much art as science! Many a rolled star is smooth so the fire blows by before the star lights, so a smooth prime may help but a smooth prime roughened by some 4FA will help a lot. Also primes are used sometimes to separate incompatible compound such as chlorate stars and BP burst charges. 

[LiamPyro]

19 hours ago, Zumber said:

Two prime stage works all well for me even if shell is bursted using just flash powder.

At first stage use slow burning prime that has high charcoal percentage and add 5  to 10 percent 200 mesh magnelium in it and 10 percent barium nitrate in it.

Second stage is just screened bp mixture that burns slower than milled bp.

How high of a charcoal percentage do you use in the first layer? Does it leave a noticeable trail in the sky before the star composition ignites?

[Zumber]

4 hours ago, LiamPyro said:

How high of a charcoal percentage do you use in the first layer? Does it leave a noticeable trail in the sky before the star composition ignites?

Just like c6 but it is modified by adding barium nitrate and 200 mesh magnelium to make it even hotter to lit hard lit stars.

Yeah it leaves visible trail behind like streamer effect.

[Kalifireworks]

It is very Important to make your stars as wet as possible, you need to make them as close to all sticking together as possible, the stars surface should look very wet and rough, Sticky. Only at this stage you should add your first increment of prime.

 

I found this to be very Important to get proper ignition, I virtually have no blind stars anymore even with flash only hard broken inserts and simple BP + Sic Prime.

 

 

Everbody is always trying to make the hottest of the hottest prime by adding all kinds of stuff to the prime, eventho the real issue for blind stars is not the prime burning to cold but more improper priming technique

Edited July 21 by Kalifireworks

[LiamPyro]

On 7/20/2024 at 10:07 PM, Kalifireworks said:

It is very Important to make your stars as wet as possible, you need to make them as close to all sticking together as possible, the stars surface should look very wet and rough, Sticky. Only at this stage you should add your first increment of prime.

What does the excessive wetting do? Meld the prime with the star better? I actually used a pseudo step-priming technique where I gradually transitioned from star comp to prime using a mixed spoonful of star comp /prime, so I don’t think that it was an issue of poor mixing at the interface. What do your finished stars look like? Are they all dusty or smooth… and is the final layer milled BP +Si?  

[LiamPyro]

I’m actually planning to execute an experiment where I take rolled stars from the same batch and prime quantities of 10 of them using different methods, then add them to small flash broken cake inserts to create an environment where they won’t light easily… the cake insert that displays all 10 stars (100% ignition) wins.

[Zumber]

6 hours ago, LiamPyro said:

What does the excessive wetting do? Meld the prime with the star better? I actually used a pseudo step-priming technique where I gradually transitioned from star comp to prime using a mixed spoonful of star comp /prime, so I don’t think that it was an issue of poor mixing at the interface. What do your finished stars look like? Are they all dusty or smooth… and is the final layer milled BP +Si?  

Neither too much water is added to wet stars nor too little so that prime must not stick to star.

It should be optimum, it takes practice and experience to become skillful....if you add prime to star dry prime powder must not rest at bottom of star roller tumbler at this stage stars are not wet enough. If too much water stars stick together.

 

[Kalifireworks]

On 7/24/2024 at 11:30 PM, LiamPyro said:

What does the excessive wetting do? Meld the prime with the star better? I actually used a pseudo step-priming technique where I gradually transitioned from star comp to prime using a mixed spoonful of star comp /prime, so I don’t think that it was an issue of poor mixing at the interface. What do your finished stars look like? Are they all dusty or smooth… and is the final layer milled BP +Si?  

Prime is never milled. And I use only BP + Sic, nothing else before that, straight on top of the color, cant see a single blind stars when breaking very hard

[LiamPyro]

8 hours ago, Kalifireworks said:

Prime is never milled. And I use only BP + Sic, nothing else before that, straight on top of the color, cant see a single blind stars when breaking very hard

Ah! Thanks for the info. The option to have extremely hard breaks without the fear of blind stars is what I’m after. Are you adding 5% silicon, or more? How thick is the layer of prime, do you measure by cutting into a star or use a certain percentage of the star weight in prime weight? 

[Zumber]

2 hours ago, LiamPyro said:

Ah! Thanks for the info. The option to have extremely hard breaks without the fear of blind stars is what I’m after. Are you adding 5% silicon, or more? How thick is the layer of prime, do you measure by cutting into a star or use a certain percentage of the star weight in prime weight? 

It depends on stars.

For more hard lit stars upto 10 percent silicon could work.

I prime my stars by weight i.e.

100 gram star composition is taken and 25 to 35 percent of prime by weight is kept aside once i finish rolling stars I add prime.

If you want streamer type effect then turns colour stars add 10 to 20 percent charcoal in standard bp followed by 10 percent 200 mesh magnelium and apply it over silicon prime layer.

[Kalifireworks]

On 7/26/2024 at 8:29 AM, LiamPyro said:

Ah! Thanks for the info. The option to have extremely hard breaks without the fear of blind stars is what I’m after. Are you adding 5% silicon, or more? How thick is the layer of prime, do you measure by cutting into a star or use a certain percentage of the star weight in prime weight? 

50% by weight is a good ammount, measure by cutting the star in half. I add arround 10%, some like to use a really silicon heavy comp with 30% or so and plain BP on top.

 

Silicon is really amazing stuff for primes

[LiamPyro]

7 hours ago, Kalifireworks said:

50% by weight is a good ammount, measure by cutting the star in half. I add arround 10%, some like to use a really silicon heavy comp with 30% or so and plain BP on top.

 

Silicon is really amazing stuff for primes

Ok, good to know. I’m currently working on the aforementioned prime comparison experiment. Will post the results if they are significant. The main variables I’m testing are the effect of mill time on prime and the effect of additives such as silicon and sawdust.