28 replies to this topic

[Pirotex]

Name of composition: Flashing microstars

Composition Type: effect star

Creator: Ronald Lancaster

Color/Effect: flash of light after a short delay

Preparation: 100 grams of the mixture is kneaded with 20 grams of a 10% nitrocellu-lose solution in acetone to form a homogeneous mass. It is rolled out on a star plate of about 8- 10mm thick and cut into a few pieces. These are dried at room temperature for one day and then further dried in an oven at 50°C for five hours.
They are then crushed into angular grains with a wooden mallet and an aluminium roller. Finally the grains are separated through a sieve to obtain small stars of 1.5 to 3.0 mm.

 

Version 1:

Barium nitrate 40%
Sulfur 20%
Magnalium (50/50) 40%

 

Version 2:

Stroncium nitrate 30%
Sulfur 30%
Magnalium (50/50) 40%

 

I maked version 2 with 5% dextrin and formed 1.5 mm grains. Use in fountain 20 mm with BP 60/33/7 + 10% microstars.

For this fountain need slowly BP, for example 55/35/10 or 50/38/12 (from book)

More information in R. Lancaster FIREWORKS Principles and Practice 3rd Edition, page 150

 

VIDEO: https://www.youtube....h?v=rfXSBFJuzCI

VIDEO 2: https://www.youtube....h?v=HBFn4NgxkvI

Edited by Pirotex, 18 March 2017 - 06:53 AM.

[MudDuckPyro79]

Nice pirotex. Love em sparks

[parthoasia]

very nice pop sir!

[Nitrotitanite]

a really nice effect

[OldMarine]

What mesh do you use for the magnalium?

[dagabu]

Absolutely gorgeous!

[OldMarine]

Absolutely gorgeous!

I liked it so much I just bought the book. I added Piro's rendition of those to my personal formulae on FW as well. I love me some gerbs!

Also started a thread there on these stars as well.

Edited by OldMarine, 18 March 2017 - 02:02 PM.

[mabuse00]

Great stuff

 

I wonder why this actually emits green an red light, in absence of any chlorine donor and with so much metal.

 

What diameter had the nozzle?

[Pirotex]

OldMarine, 200 mesh

mabuse00, 10 mm

Edited by Pirotex, 18 March 2017 - 02:39 PM.

[PyroCreationZ]

Very nice result!

[OldMarine]

MgAl definitely needs to be on the small side of 200 mesh. My stars are hitting the ground before ignition. They have a smolder phase similar to crackle and strobes so the size of the metal definitely affects that delay time.

[NeighborJ]

I believe if you reduce the amount of sulfer it will have the same effect. It sure has a lot of the stuff.

[OldMarine]

Got another 100 gram batch with the finer MgAl made up and rolled out before the rains came in. Got it in the doghouse getting rid of the acetone and I'll put it in the dehydrator tomorrow. The scraps I tested are performing much better with only a slight delay.

I dried the strontium nitrate overnight in my dehydrator before mixing and it seems to have helped the color.

Edited by OldMarine, 20 March 2017 - 07:38 PM.

[Ubehage]

I believe if you reduce the amount of sulfer it will have the same effect. It sure has a lot of the stuff.

What is Sulfur's role in this composition? Is it fuel?

[NeighborJ]

I see sulfer as a slag producing fuel which can be adjusted to increase or reduce the delay timing. The MgAl is just a light producing fuel which produces little slag but will still contribute to the delay by consuming oxidizer.

[Sulphurstan]

Definitevely gonna try these! These cuties have a nice effect!

[OldMarine]

Apparently Piro either had some other colored stars in the fountains or the color is a camera artifact. Though these make a wonderful bursting shower of sparks, I nor Ned G. have been able to get a bit of color from them and Ned did further reading and came up with this (from Fireworking.com)

Ned quoted: "Pat, I think that there may be some confusion about the effects we're talking about. Upon following Mike's advice, and perusing Shimizu's exploration of "microstars" in PT 10, I realize the effect that is being striven for is the popping, branching white/silver sparking effect we're seeing in the vids of Pirotex's gerbs. The colored microstars that we're seeing in there must be being produced by actual colored microstars, different than the flashing microstars we're exploring in here. 

 

Shimizu discusses an effect similar to a crackle one or a strobe one, where there is ignition, a smoulder phase, and then the popping/sparking effect phase.

 

I was under the impression we were looking to get a green or red colored star effect from Lancaster's stars, but, nope, that's not what we're looking for." End quote.

 

Still a nice effect but not what I thought....

[dynomike1]

I think this is where the misunderstanding might have came from. "flash of light after a short delay". Sounds like the star was a color till it burnt to the crackle. I the video the ones that i saw retained their color didnt crackle.  

[Pirotex]

Green stars in my fountain (1,5-2 mm):

Ba(No3)2 - 50%
Magnalium - 25%
PVC - 10%
S - 10%
Dextrin - 5%

[OldMarine]

Green stars in my fountain (1,5-2 mm):

Ba(No3)2 - 50%
Magnalium - 25%
PVC - 10%
S - 10%
Dextrin - 5%

Ah, there's the missing chlorine donor!