55 replies to this topic

[insutama]

To make a long story short...

 

just try it.

 

Copper oxide (black)..........68

MgAl 250 mesh..................30

Bismuth trioxide....................8

 

Mix, wet with nitrocellulose laquer untill it is a messy putty like substance. Let it dry until it can be crumbled.

Push trough a screen to granulate, let it dry.

Sieve the grains for different sizes/purposes.

Light one, get your brains pulled out of joy ; )

 

larger ones can be primed with standard BP (they light very easy)

smaler ones can be used in comets without any priming.

 

NO MORE TOXIC LEAD!!! 

 

yay!

 

and.... why the F*** can't i post video's to my gallery???

 

 

Still use 10% NC ?

[Seymour]

Flashman, I've used Resinox which is a kind of phenolic resin. 3-4% "wetted" with IPA or acetone worked for me.

 

This stuff is a solid resin solvent activated. I have not tried the two part curing phenolic resins.

[Mia]

Try the guys over on http://www.pyro-gear.co.uk/

 

They've done a ton of it, and have had a couple of articles published in American Fireworks News about it.  It's still a "work in progress", but seems to progress well.

 

LLoyd

Yes they have done some remarkable work, but getting in to the site to see the work requires to sign up and get the admin to give you access to the hidden section well worth it though.

[lloyd]

BS!  Read the AFN articles!

 

There's nothing 'secret' about it, or they wouldn't have published it, um..., "publicly".

 

Lloyd

[RichardH08]

Lloyd is quite right. The only motive for restricting access to some of the material on that site is that it isn't yet ready for release. Much of the content relates to 'off-the-wall' ideas that don't always work out. Successful projects are made public as soon as is feasible, usually via a submission to AFN because we believe it is a publication that deserves to be supported.

[Fulmen]

Just so we're clear on the mesh size of the MgAl: Coarse gives single bangs in large stars, finer gives single bangs in small and multiple in large?

Edited by Fulmen, 18 March 2016 - 11:12 AM.

[lloyd]

That's about right, Fulmen; but with a caveat.

 

Fine material may cause just one tiny explosion on a large star, then extinguish that star, so the bulk of the star's mass goes wasted.

 

The ideal situation is to size the stars according to the mesh size, so that each gives one bang.  Since the finer material makes smaller stars, you compensate for the 'one bang per' issue by making more stars (which will fit in the effect, because they're smaller).  They can be made really tiny with finer Mg/Al.

 

Lloyd

Edited by lloyd, 18 March 2016 - 11:26 AM.

[Fulmen]

Good point, Lloyd. While I can see some interesting uses for a tuned multibang composition, it's probably not worth the extra work. Keeping it simple is never wrong, as I only deal with small devices I can probably stick to one or two mesh sizes.

[OldMarine]

How "tight" do mesh sizes need to be for consistency of timing and obtaining a single crack? Are the meshes offered by most suppliers close enough? I think August is the only one offering single mesh batches and that's precious as hen's teeth.

[lloyd]

Patrick,

So long as the grain size is appropriate to the Mg/Al size (so that each grain cracks only once, loudly), the particular exact size is not as important as size consistency.  I used 'stock' 6-mesh and 8-mesh screens from McMaster-Carr.  Careful classification of the particles to sit between the two screens was enough for the timing consistency you saw in that video I posted on PF.

 

As important - I think - is getting the particles as nearly spherical as possible.  You don't wan't 'worms' of comp.  That's why I recommend a sort of 'rolling' action to get the almost-dry comp to pass a particular mesh, rather than a pressing/scraping motion.

 

Your choosing a thick-wired 6 and a thinner-wired 8 to minimize the size differential between them might help achieve even more precision, but I don't think it's necessary to go to those extremes.

 

Lloyd

Edited by lloyd, 19 March 2016 - 07:07 AM.

[patsroom]

Copper oxide (black)..........68

MgAl 250 mesh..................30

Bismuth trioxide....................8

I really would like to make some crackling eggs! But I can not find MaAg 250 mesh, the best I can find is something like 200 -350 mesh and I am not sure that would work. I do not have a lot of money to spend to find the right mixer (penny pincher)  . I like forumuals that work right out of the box in order to save cost. I know that this hobby can cost. But if someone could let me know of a good MgAl mesh size and forumual ratios that would work that would be great. I do thank thoses that can help............Pat

 

PS Or if someone knows where to get 250 mesh AgAl that would be great.

Edited by patsroom, 05 August 2016 - 03:21 PM.

[OldMarine]

I've tried it since my last post and used my 200-325 mgal. I was pleased with the results. Nice single cracks.

[patsroom]

OldMarine Thanks, That was fast  ............Pat

[OldMarine]

As Lloyd stated above, you need to size the granules for even performance. I had some larger scraps that would pop on one side and shoot the rest across the yard unlit.

[patsroom]

As Lloyd stated above, you need to size the granules for even performance. I had some larger scraps that would pop on one side and shoot the rest across the yard unlit.

When you say granules size I take it to mean the crackling egg mixed and dry. That why they all will pop at the same time when lit......................Pat

[OldMarine]

Yeah, the finished product should be consistently sized.