34 replies to this topic

[karlfoxman]

I've just made some 3/4" cavity comets using Williams no Antimony glitter. The formula is:

Potassium nitrate 55*
Sulfur 7*
Charcoal Pine 17*
Red Iron Oxide 4
Aluminium 325mesh 10
Magnalium 50:50 3
Dextrin 4*

*Ball mill for 1hr

The cavity will be filled with Veline blue.

Heres a picture of them drying, I must say that Williams no Antimony is one of the most lovely glitters around!

[karlfoxman]

Just filled the cavity comets with a Violet formula, here is the formula:

Strontium nitrate 30
Potassium perchlorate 20
Parlon 20
Copper oxide 10
Aluminium atomized 325 mesh 10
Dextrin 4

I will post a video when I fire them.

Here is a picture

[italteen3]

Karlfoxman those comets look B-E-A-UTIFUL!

How did you wet, dry, and fill the cavities? I know my first attempt at cavity stars did not fair so well as I over-wet the whole batch and the walls of the cavity slumped. Others crumbled but I had this last batch just right, just don't know what to fill it with!

Can't wait to see the video.

[karlfoxman]

I pumped the cavity comets first, then let them dry out for a day. Then fill the cavity with the other formula, in this case a Violet one. I tested one last night and it worked great, the violet is a lovely colour! I have made two 4" shells with these in them, I used 8 per shell in a palm tree fashion. I have some pictures.

[al69]

those are two mighty thick hemis. should make a decent bang
should look really nice though, i love palm tree shells, especially with 8 comets... thats a lot!

[Pretty green flames]

Karl, what is the average drying time for your comets? Do you speed the drying procces in any way by using a drying/dehumidifier box?

[karlfoxman]

Depends what comp im using, these took 2 days to dry. I dont force dry them in any way. They dry in the air. We have had a few days of hot weather so that helped!

[alany]

2 days? Are you sure they are really dry?

[karlfoxman]

Well they were left for 4 days total before I closed the shell, they were dry when I closed the shall as were the others. I Fired the shell and the comets all lit, the one on the top of the shell was lovely and the burn time was perfect from what I could see.

[italteen3]

Whoa takes my 1" comets, though they are about 44% AF Charcoal, over a month to dry on its own. Hopefully no more then a week in my drying box. So humid here that it takes forever for any of my charcoal based stars to dry.

Any vids?

[RegimentalPyro]

A lovely looking couple of shells there. Are you using the "fuse-after-pasting" method of fusing there, or a spolette?

BTW - Karl is quite right - Williams no-antimony glitter is one of the finest glitters available. It's certainly one of my favourites. Whilst it *does* use magnalium, it only comprises 3%, and is thus very economical. The rest of the ingredients are quite common.....

I really look forward to seeing this in action.....

[karlfoxman]

Cheers Regi, yeah its a top quality glitter formula. I have loads and loads of magnallium so its not a problem, though nice that it requires only a small percentage of the lovely silver dust Ill post the video, but its in mobile phone format so quality is poor.

The time fuse is added after pasting like this:

First I make a small tube just big enough to take 1/4" time fuse and long enough to reach the center of the shell, its sticks out the bottom of the shell by about 5mm. I close the shell and paste it, then cut my fuse to size. Punce one crossmatch hole at one end and cut the fuse diagonal to expose more powder. I put 5 strands of blackmatch down the tube and push the time fuse inside. The I wrap string soaked in glue around the joint to stop flowerpots. I might add that with the number of shells I have fired this has never failed me. For 5" and above I use double time fuse if possible.

4" Palm tree DIVX

[pyrotrev]

I've just made some 3/4" cavity comets using Williams no Antimony glitter. The formula is:

Potassium nitrate 55*
Sulfur 7*
Charcoal Pine 17*
Red Iron Oxide 4
Aluminium 325mesh 10
Magnalium 50:50 3
Dextrin 4*

*Ball mill for 1hr

The cavity will be filled with Veline blue.

Heres a picture of them drying, I must say that Williams no Antimony is one of the most lovely glitters around!

Hi Karl

What particle size was the MgAl please?

[BrightStar]

Hi Karl, a few extra questions please....

Do you use any prime for these comets? Is the glitter comp hot enough to ignite the colour comp reliably?

How firmly do you glue the comets to the hemis? I noticed that they were fixed with colour side out... does this have any effect on the burn?

Thanks for all the project inspiration!

[karlfoxman]

Pyro trev: I believe its 100-200 mesh.

Brightstar: The comets were not primed, they are glued with a dab of hot glue. Next time ill paste over the cavity end as I think the purple was thrown from the cavity and did not light. The purple is very nice though and works well with the Williams no Antimony glitter. When I paste them I will paste only the very end so at least 3/4 of the comet is exposed to the open. They light well because the sharp edges. You could prime them with meal and dextrin paste and then a final dip in powder.