Microstars for Gerbs

[gizmothegecko]

Hello everyone, I’m currently looking for reliable colored microstar formulas specifically designed for gerbs. While I’ve had success with red stars, my attempts at blue and green haven’t worked—they either burn up entirely or go blind. I’m using a 60/30/10 base composition, which seems to work well for red stars, but I’m wondering if this mix might be unsuitable for other colors. Unfortunately, detailed information about microstars for fountains seems hard to come by. If anyone could share proven formulas, adjustments, or tips for creating durable colored microstars that perform well in gerbs, I’d greatly appreciate it!

 

[Zumber]

I haven't made blue ever but have successfully prepared red, green, white microstars and tested it in mini fountain contains 100 gram of BP and 35 gram of micro stars mixed and pressed into fountain tube.

 

[Carbon796]

There are a couple techniques that come to mind for both matrix comets and fountains. But, based on your description. If stars are going blind, it's generally a priming problem. If they're burning up to soon. It's a comp speed issue. Or the stars are not releasing from the base comp soon enough.

Are you using the equivalent grn formula, as the red ?

Have you timed each individual comp ? Ideally you would tune each individual star comp. To burn at near the same speed. To get reliable results, regardless of color/effect. It's beneficial if the star comp is slower than the base comp.

What nominal size are the fountains your building ?

What is the average effect height of them ?

[gizmothegecko]

Thank you, Zumber, for those compositions. I’ll try them out this week and use them in a couple of gerbs. Also, could you send me the white microstar composition if you don’t mind?

In response to Carbon: I haven’t tried the equivalent green formula yet, but it seems like Zumber’s recommendation is equivalent. From what you’re saying, I should find a formula that burns slowly enough to be ejected properly and tune it to match my base composition. I’ve been using a base composition of 60/30/10, which works for my red stars and dragon eggs, but I’ll work on fine-tuning it to adjust the burn speed and other properties.

I’m using 3/4-inch ID tubes that are usually 4 to 7 inches long, depending on how much composition I make. The 60/30/10 formula gives a height of about 3 feet, and the stars are ejected to that height or slightly higher.

Another issue I’m having is with more delicate compositions like blue and yellow. These stars seem to burn up immediately because of the heat from the base composition. I’m considering adding a slow-burning composition over the star to protect it until it exits the gerb, but I’m not sure if that will work. I’ll give it a try.

If you have any suggestions to fix this or know of good blue or yellow compositions, I’d really appreciate it. Thanks for the input, everyone!

 

 

[Carbon796]

To me 3ft sounds low for a 3/4" gerb. I would expect more in the 5-7ft range. You may want to try 65/25/10.

If you take all of your color comps ( press or ram a #4 spolette 1" ) for each color/effect. Then burn and time them. You can then tune the faster ones to match the burning speed of the red that works well for you. That way they should all work as well as the red. And the effect will be consistent regardless of the star color. You should also time your base fountain comp as above. And ensure that it is faster than your star comps.

Blue. Try searching on here for " blue Chinese micro star " or something to that effect.

 

Edited December 2 by Carbon796

[cmjlab]

I'm assuming OP has been using water for both microstars and the fountain comp. 

If so, I wonder if OP still used water to dampen the fountain mix, but bound the colored microstars with nitrocellulose, if that wouldn't help keep the star from burning up inside the tube, and ensure the dampness from the fountain mix doesn't mess with the microstars.

[Zumber]

12 hours ago, Carbon796 said:

There are a couple techniques that come to mind for both matrix comets and fountains. But, based on your description. If stars are going blind, it's generally a priming problem. If they're burning up to soon. It's a comp speed issue. Or the stars are not releasing from the base comp soon enough.

Are you using the equivalent grn formula, as the red ?

Have you timed each individual comp ? Ideally you would tune each individual star comp. To burn at near the same speed. To get reliable results, regardless of color/effect. It's beneficial if the star comp is slower than the base comp.

What nominal size are the fountains your building ?

What is the average effect height of them ?

I second with speed of star, it shouldn't be too fast to burn itself in a gerb but I disagree on priming stars. I always use unprimed stars in a fountain; primed stars might create additional gas which unnecessary increases pressure in gerb also base mixture is slow burning bp, if prime is faster enough it increases burn rate of base mixture too.

Edited December 2 by Zumber

[Zumber]

9 hours ago, gizmothegecko said:

Thank you, Zumber, for those compositions. I’ll try them out this week and use them in a couple of gerbs. Also, could you send me the white microstar composition if you don’t mind?

In response to Carbon: I haven’t tried the equivalent green formula yet, but it seems like Zumber’s recommendation is equivalent. From what you’re saying, I should find a formula that burns slowly enough to be ejected properly and tune it to match my base composition. I’ve been using a base composition of 60/30/10, which works for my red stars and dragon eggs, but I’ll work on fine-tuning it to adjust the burn speed and other properties.

I’m using 3/4-inch ID tubes that are usually 4 to 7 inches long, depending on how much composition I make. The 60/30/10 formula gives a height of about 3 feet, and the stars are ejected to that height or slightly higher.

Another issue I’m having is with more delicate compositions like blue and yellow. These stars seem to burn up immediately because of the heat from the base composition. I’m considering adding a slow-burning composition over the star to protect it until it exits the gerb, but I’m not sure if that will work. I’ll give it a try.

If you have any suggestions to fix this or know of good blue or yellow compositions, I’d really appreciate it. Thanks for the input, everyone!

 

 

I haven't made that much small ID gerb.

The video shown in video is for 2 inch ID tube and height was 5 to 6 inch in which 90/30 or 100/35 BP/stars mixture pressed dry manually using hand press.

For yellow ,I recently tested composition shown above and ratio was 70/20 Green/red star composition mixed together. For white I have used

Barium nitrate 4.5

Coated Magnelium 200 mesh- 2.0

Sulphur -1.5

Dextrin-0.5

Weight by parts not percentage.

[Mumbles]

Just stopping in to share some tips I've heard of and learned.  

You're going to want to ensure you don't have a flat interior on your fountain nozzle. A tapered or curved interior to the nozzle helps to ensure the stars get directed toward the exit hole, and don't get hung up or stuck and just burn inside the fountain. I've heard that this can also occasionally lead to the fountain clogging up or exploding.

I like to keep my microstars at least 1/2, but preferably 1/3 the diameter of the nozzle.  The thought being if two try to exit simultaneously, it's harder for them to get hung up on each other at the vent.

A friend of mine who makes great microstar comets swears by a barium nitrate based outer/prime layer. A composition similar to the white microstar formula Zumber gave is the type of thing he was using. It's not for ensuring the stars light or anything like that. He likes to have kind of a sacrificial layer available to burn either in the matrix comet or in the first little bit of the tail. He thinks it allows the stars to get a little bit farther away before burning whatever color. He also claims that the heavier barium nitrate based outer layer makes them drop away out of the tail better. Whether any of that is actually true or happening in practice, I'm not sure. The results are quite impressive though.

I also tended toward fountain compositions with a base of BP with added charcoal, nitrate, sulfur, metal, etc. Compositions made with a base of BP always seemed to burn a little cleaner and a little more vigorously for me in fountains compared to the equivalent composition just using screened together components.  My feeling was always keeping the fountain composition base faster and cleaner burning helps to expel the microstars better.  I'm not sure if there's a lot of truth to it, but I've always liked the results.

[LiamPyro]

I have been wanting to incorporate microstars into fountains and rocket delays as well. One idea I’ve seen thrown around is to prime the microstars with a delay composition to help prevent them from burning up inside the device, along the same lines as the “sacrificial” layer mentioned above. “Glusatz” might work well for this purpose. I’ve made it before and it does function well when pressed in a column to produce an extremely slow “glow fuse” delay element that burns around 30 sec /inch. I have yet to try coating stars with it. Might be worth a shot, the idea being that small color cores coated with it will have a delayed action that allows their brief color output to occur once the stars are ejected and nearing apogee, potentially allowing for a smaller star to have a similar visual effect as a larger star that begins burning before exiting the nozzle… that’s my logic at least. Keeping the stars as small as possible has obvious advantages of allowing for more star density in the spray and less chance of clogging the nozzle.
 

The formula for Glusatz is below. More detail can be found in the match crackers section of John Donner’s “A Professional’s Guide to Pyrotechnics, Understanding and Making Exploding Fireworks”.

Glusatz: 

Barium nitrate 75.5 
Charcoal (AF) 10 
Sulfur 10 
Meal 3 
Cab-O-Sil 1 
CMC 0.5 
Distilled water +6 (dissolve CMC first then add remaining ingredients)

Edited December 3 by LiamPyro

[SKC]

Please observe the mistakes I have done in making microstars in my fountain. They are around 5-6mm in size and are not primed. As a result the spread is not good. Audience says it's good but it should have been better. I have already made Red+Green microstars for fountain to be made on 31st. Will post the pictures when at home. I am planning to prime them as it allows some time to each star to come out before they expose colour. To ensure 90-95% burn I am planning to sift them with slow flash before before loading into fountain casing. I am quite hopeful that result will improve a lot.

[SKC]

These is the size of Microstrars before priming.

[Zumber]

2 hours ago, SKC said:

Please observe the mistakes I have done in making microstars in my fountain. They are around 5-6mm in size and are not primed. As a result the spread is not good. Audience says it's good but it should have been better. I have already made Red+Green microstars for fountain to be made on 31st. Will post the pictures when at home. I am planning to prime them as it allows some time to each star to come out before they expose colour. To ensure 90-95% burn I am planning to sift them with slow flash before before loading into fountain casing. I am quite hopeful that result will improve a lot.

What base mixture composition do you uses?

[SKC]

On 12/6/2024 at 3:30 PM, Zumber said:

What base mixture composition do you uses?

The base composition for my fountain is

KNO3-4

CHARCOAL-2

SULPHUR-1

[Zumber]

Thank you..!!