Tro de bac

[displayfireworks1]

We were talking about the "Valencia Firecracker" "TRO DE BAC" in the Spain section of the forums. For those that do not know this is a throw down type firecracker. If someone knows the formula to make these please post it here in the Fireworks Manufacturing section.
http://www.fallasvalencia.es/files/A13-443157044.jpg?1267431836
http://www.vivelasfallas.es/sites/default/files/imagenes/story/Tro_de_Bac_0.jpg

[displayfireworks1]

Message I received.
.
.
50% potassium chlorate
40% antimony trisulfide -325 pyro grade
10% sulfur

Uncoated aquarium gravel Walmart

9/16" paper tubes plugged at one end with paper plugs.

.
If anyone agrees or disagrees please comment or post another formula

[countryboy7978]

Message I received.
.
.
50% potassium chlorate
40% antimony trisulfide -325 pyro grade
10% sulfur

Uncoated aquarium gravel Walmart

9/16" paper tubes plugged at one end with paper plugs.

.
If anyone agrees or disagrees please comment or post another formula

The above mix is a close representation of what would be in the tro de bac however just like here, the composition varies by manufacturer. One could use 50:50 chlorate to antimony although they tend to require a much higher activation energy as the sulfur increases the friction sensitivity. The actual mixture should not exceed 3/4 gram as they should not be able to cause amputation, although one of these going off in your hand or pocket would definitely require an ER visit. Keep in mind these items also throw gravel, as it is needed in the mixture for the devices to function. Use glasses or goggles, and wear pants. I've learned my lesson wearing flip flops.


The actual tro de bac seem to be made from hand rolled paper tubes that are folded over on the bottom, then pasted with gummed kraft tape to seal the tops and fortify the bottom. Pre-made spiral tubes with thin walls would be easy to use or you could hand roll some using kraft or even newspaper around a 1/2" dowel.

The tro de bac mixture is mixed wet. The gravel is wetted and the dry components are diapered in, then loaded and pasted while still wet. This makes their handling much safer as the workers do not appear to have any safety equipment. The finished salutes are then left to dry in the sun.

[displayfireworks1]

When they are making the device in this video the mixture looks relatively stable. when they diaper mix these are these the pieces of rock already coated?

https://www.youtube.com/watch?v=pNIkN6DMyzY

[displayfireworks1]

I think he is making a similar device in this video.

https://www.youtube.com/watch?v=uSPSWhGy528
.
I saw a video he had setting one of these off but I cannot seem to find it. I think these are too big. He using the Cherry Bomb cups to simplify the assembly.

[countryboy7978]

From what I've read on tro de bac, the gravel is moistened with water and the dry chemicals are slowly diapered in to the wet gravel. What I'm not sure about is if the chemicals are mixed first then diapered into the gravel or if the separate components are diapered in one at a time with the gravel. I would venture to guess that they are added in one at a time with the antimony first, then the other two components added secondly. When the mixture is wet, it is not sensitive to ignition, and according to the articles I've read there had never been an accident during the manufacturing of these firecrackers. The women making these seem to knock them around quite a bit. The tubes are made from what looks like a few turns of thin kraft paper, then pasted over twice with gummed kraft tape. This allows them to dry faster than they would if enclosed in a spiral tube with thicker walls. Once dry they are ready to be shot off.

In the chemist's video he is using chlorate and realgar which is slightly more toxic than antimony and the way he packs the mixture in until it crunches makes me cringe even if it is wet. I'd stay away from this and the much more deadly Armstrong's mixture. That stuff is much more powerful and very sensitive. I've seen what a 1/2 gram will do to a person's leg through a pair of jeans.

[countryboy7978]

Also Mike the Chem45 took down some of his videos. I'm not sure what happened to him but he up and disappeared.

[displayfireworks1]

TheChemist45 is a member of the pyrotalk forums. A few people that are no longer active on the forums offended him. As you can tell by his videos TheChemist45 is a little eccentric. Some people just do not know how to understand someone that is different, they picked at him until he left. I tried to convince him this group is gone from the forums and please return put he never did.
Back in 2011 TheChemist45 convinced me to send him the large Black Cat tube in this video minus the inner cake of course. He wanted to add it to his collection. I sent it to him free of charge. You can see it in this video at 5:10 min.

https://www.youtube.com/watch?v=87rC4l158ho
,
The Chemist45 posted a video of these going off but I can not seem to find it. He may have removed some of his videos.

[NWPA]

I for one enjoyed the chemist45 videos. This is a person who truly, truly loves fireworks. You can't help but sense that in watching how he handles all his treasures. I hope all is well with him.

[PGH_Pyro]

Love his vids but yeah he seems to have vanished.

[PyroManiacs]

Its a shame. :(