Improve prime meal with metals

[MinamotoKobayashi]

Hello.

It is useful to enhance fast meal BP with some kind of metals like 10% of MgAl 325 mesh to obtain a better prime performance?

Usually I use hot meal BP for some kinds of stars, but not all the stars ignite because they lost the prime during the break up

as shown in this video:

 

https://youtu.be/_PiWxoknRvY

 

 

 

[kingkama]

Is better use simple hand mixed BP for Priming with a 10% MgAl or perchlorate Priming, in the video may be a too strong break the reason for stars misfire,

[pyrokid]

An interesting prime composition I recently came across is

 

33 wt% potassium nitrate, 24.5 wt% silicon, 20.8 wt% black iron oxide, 12.3 wt% aluminum, 3.8 wt% charcoal, and 5.6 wt% nitrocellulose in acetone

 

This composition seems extreme but in general metals can be added to increase the burning temperature. Silicon or iron oxide + aluminum create hot slag which provides superior heat transfer to the next composition. Other options include reducing the strength of the break charge or rolling a thin layer of some composition with a higher wind resistance such as charcoal streamer.

[Arthur]

One false path that people go on with primes is to make them too fast.

 

If a star is hard to light then use a slow prime this lets the prime fire sit on the star pellet for some time after the launch transferring more heat to the star than a fast prime could. Also something that burns with slag transfers all the heat in the slag to the ignition point where as a prime with gaseous products transfers all the fire heat to the sky.

 

A damp paste of 100mesh BP ingredients with 5% 200mesh silicon powder added will form a slow but hot prime, if later dipped in 2 to 4 FA powder the surface ceases to be smooth and is granular, so taking fire very readily.

 

Consider the ingredients in a prime system -liquids in the products will lose heat to the star gasses will lose heat to the atmosphere. Silicon will give liquid silica which will cool in contact with the star and pass a lot of heat, aluminium will make alumina dust as smoke so it's heat is largely lost. We've all seen poor BP burn leaving molten globules in the slag -that passes a lot of heat to the star surface, BUT fast BP burns to a hot gas which expands away from the star surface (try burning good fast BP on a paper -shouldn't be a mark, burn ingredient mix on a paper and the paper is burned and that's exactly what a prime should do.

Edited March 30, 2018 by Arthur

[OldMarine]

I use screen mixed BP with 15% silicon for a final prime on most everything.

[MinamotoKobayashi]

Hello and thanks for all the replies.

I discovered that some stars lost their prime in the break for some reasons.

The use of acetone and using a star plate did the walls too smooth and compacted and the prime do not stick correctly.

 

I also found a system to stick the prime to the star walls much better: I put the stars in a kitchen strainer, I wet them spraying

a mixture of deminaralized water plus 5% isoprophil alcohol plus a spoon of dextrin every liter (as NeighborJ suggested me), and while shaking the stars I flour over some fast BP meal+325 mesh MgAl since the stars are sorrounded with a thin layer of BP paste. It is important to not use too much water, or the stars will stick one to another.

At this point I spread the stars over a wax paper full of dried fast BP meal+MgAl, and while pulling the edges of the wax paper in two opposite directions, I made the star rolling over ther fast BP.

This create an homogeneous rock solid layer and, when dried, very easy to ignite.

I will try them inside a new shell asap

 

I use fast BP only for the stars that are easy to ignite.

I use the prime made with the classic pulverone for the other kind of stars like golden glitters that need slow burning prime to ignite correctly.

For the carbon based stars like Tiger Willow Diadem Extra I do not use any prime.

 

x Pyrokid: interesting prime. Can be applied on every kind of stars?

Edited March 30, 2018 by MinamotoKobayashi

[Arthur]

ONE of the reasons that there are so many primes, is that there are some chemical incompatibilities possible between some star comps and some prime comps, so every formula needs checking for compatibility in it's intended use.

[MrB]

ONE of the reasons that there are so many primes, is that there are some chemical incompatibilities possible between some star comps and some prime comps, so every formula needs checking for compatibility in it's intended use.

I cheat, and use only Veline for colors, so i don't have that kind of issue anymore. But a few years back when it was an issue, i simply put a delay composition on all stars, and primed on top of it. Sorts that problem out real nice.

[pyrokid]

@MinamotoKobayashi KNO3 compositions are incompatible with AP stars. I would reserve this comp for hard to light stars because of its relatively higher price.

[MinamotoKobayashi]

Hello Pyrokid.

I cannot make AP stars because I'm unable to find Ammonium Perchlorate here in Italy.

Also Potassium Perchlorate is forbidden in Europe since 2013 for the private users.

The only way is to find it thru not-legal channels, and it is a risky thing.

Potassium Dichromate is another chem that I'm unable to find, and since I wish to use the Veline system, I cannot apply the suggested prime for these kind of stars,

so I wish to know if Your comp is suitable for Veline stars.

[Mumbles]

I go back and forth on the fast vs. slow BP base thing all the time. On one hand slow BP leaves a lot more slag, and burns longer theoretically giving it more time to light the star. On the other fast BP burns faster, and thus hotter, and also is a more intimate mixture and potentially more ignitable. It should also be less prone to blowing out at high speeds.

 

This is also one of those topics that people only offer conjecture and no proof most of the time.

[MinamotoKobayashi]

Hi Mumbles.

At this point I could make two layers, the first of slow BP and the external one with fast BP.

Or apply the step priming procedure.

My first concern, however, is how to stick well the first layer over the pressed stars, because they have very smooth surfaces and the prime tend not to stick correctly.