1.4g cost analysis

[Swede]

Here in Texas, we have a gigantic 1.4g consumer works stand nearby, and every 4th, our family drops by to pick up consumer fireworks to fill out what little I have made. My personal favorites are the super-cheap 1.5" reloadable mortars. Today I bought a case (12 tubes, 72 shells) for $64. Driving home, I was thinking about the cost, the bang for your buck, if you will. Don't ask me why, but I decided to dissect one of these shells, weigh the materials, and figure out what it would cost ME to duplicate one of them.

 

The shell was a 1.5" pasted paper spherical shell, brocade blue. Separating the lift from the shell revealed 5.8 grams of what appeared to be a good quality BP, obviously pressed. The shell weighed 26.7 grams. Inside the shell was 4.7 grams of BP coated rice hull burst, probably 4:1, and 12.4 grams of excellent small round stars.

 

For the cost analysis, I am going to exclude the cost of the kraft paper, glue, rice, mortar tube, and packaging. Chemical prices are average, and labor is not considered. To duplicate this shell:

 

9.56 grams of BP. With KNO3 at $1.50 per pound, sulfur at $4.00/lb, and charcoal at $4.00 per pound, it would cost $2.12 to make a pound of BP. 9.56 grams is only 4.5 cents worth of BP for the whole shell, remarkably low.

 

Stars: I am going to consider them 100% potassium perchlorate. Silly, but perchlorate is the bulk of colored stars, and things like metal flake and other additives are usually more expensive anyhow. At $9/lb for skylighter perchlorate, the stars cost $0.27.

 

Time fuse: $0.12 per inch. The time fuse in this shell is about 1". Ignition fuse is about 12" of fast visco, which costs us about $0.20 per foot.

 

Hemi: The cheapest I found 1.5" paper hemis was $0.20 with many places upwards of fifty cents.

 

 

Results (and I know a lot of the stuff can be found cheaper):

 

Hemi: 0.20

BP: 0.045

Stars: 0.27

Time fuse: 0.12

ignition: 0.20

 

Homemade: 83.5 cents

Fireworks Stand: 89 cents

 

Not bad considering you get the tube, and all the grunt work is done for you.

 

Obviously we are all here to make better fireworks than you can buy, and there are a hundred sites where you can discuss consumer fireworks. There's an obvious joy in DIY and you can craft shells you cannot buy anywhere without a license. I don't know why I did this other than pure, dumb curiosity. I have always enjoyed the value of consumer fireworks - they are a lot of fun for the buck, and here we have a perfect example. It is interesting that the costs were so close. The Chinese factories buy in bulk that we cannot dream of so they can turn a profit.

 

The biggest surprise to me was the lift (excellent BP) and the beautiful little stars that look like they were moulded with a pill machine. They each are flawless, identical spheres.

[Swede]

Ever wonder why EVERY SINGLE CONSUMER FIREWORKS has a warning label: SHOOTS FLAMING BALLS!! It can be a Pharaoh's sepent or a sparkler or a cone, it'll still say "Shoots flaming balls!" Cracks me up.

 

 

 

http://www.5bears.com/firew/14g01.jpg

 

http://www.5bears.com/firew/14g02.jpg

Edited July 4, 2009 by Swede

[Yankie]

Nice analysis, I know a guy who may be able to get me a crate of 200-300 of these shells, and thought it would be great as inserts in larger shells. Whilst it may take the satisfaction away from making everything yourself, honestly, who would rather make a few hundred 1.5" shells from scratch when you can fork out some cash instead. The only place for consumer fireworks in my mind are as part of a more elaborate construction.

Would the burst be BP oh hulls or KP? On most consumer fireworks they normally use KP oh hulls to get a harder break and it saves milling the BP, correct me if I am wrong though.

Those Chinese can roll damn good stars, there is no doubt about that.

[Swede]

I can probably do a test to see if it's KP on rice or BP. I assumed it was BP. KP would be 5X the cost, but if it's needed to get a decent break, it's needed.

 

I agree on the use of these things as inserts. The lift cup cut right off. You get the lift BP as a bonus. The time fuse is pretty cheap stuff but from what I've seen it's decently consistent. As inserts, you could trim or extend the time fuse to stagger the breaks, or attempt to get simultaneous insert breaks.

 

My favorite use for these as is is in the form of a chained barrage. It can be surprisingly good; you can create a fairly dense barrage with little effort or $$.

 

Some of the cakes they were selling were massive, and priced accordingly - $80 on up for some giant 1.4g. The most bogus sales were the larger mortars - one shot devices (maybe 3" cannister? Nothing huge) for $30 to $40 APIECE. No thanks.

 

The stars, I'm convinced, are automated. I'll weigh them with a milligram scale to see the variation. If they are presses with a pill machine, they should have a strong consistency.

Edited July 4, 2009 by Swede

[Pretty green flame]

Swede, if possible, could you test the burst composition on chlorates, maybe the chinese use H3 in these tiny shells.

[Swede]

If it's H3, it should respond well to the n-phenylanthranilic acid test. I will find out what the burst is made of, but unfortunately I have WORK today on the 4th of July! Grrr... I tried to get the day off but was unable. All my preparation for nothing. It will take a day or two.

 

Happy 4th of July to those in the U.S. Other countries, grab an American friend, launch some fireworks, and claim "it's for my Yank friend, here!"

[TheSidewinder]

Nice job, Swede!

 

Might make for a good Blog entry, hmmm?

[Swede]

I should have enough pics by now to make it a reasonably interesting blog entry.

 

I ran some tests on the burst. Visually, it looks thinner than a 4:1 BP rice. If I were to guess, I'd say it's more like 3:1 or less, so yes it could be KP or H3. I took a small portion of the burst and soaked it in hot distilled water:

 

http://www.5bears.com/firew/burtst01.jpg

 

This was filtered into a small flask:

 

http://www.5bears.com/firew/burtst02.jpg

 

And added to two test tubes in small proportions. The middle test tube was tested for the presence of chlorate using fenamic acid + sulfuric acid, the now well-proven NPAA test. It came out negative. No chlorate. The next test (left test tube) was a larger sample portion, using methylene blue to test for perchlorates. In the presence of perchlorate, methylene blue forms a distinct, purple precipitate. Immediately, upon seeing the results, I thought "perc" but just to be sure, I added methylene blue to a solution of potassium nitrate, as found in BP (right test tube) to compare.

 

The results, from left to right:

 

Methylene blue perchlorate test: Positive. NPAA chlorate test: Negative. Potassium nitrate + methylene blue as a comparison. Note the nitrate blue color vs. the perchlorate purple, plus precipitate.

 

http://www.5bears.com/firew/burtst03.jpg

 

Conclusion: The burst in this 1.5" shell is KP, probably 2 or 3 to 1, on rice hulls.

[firetech]

Nice followup Swede. Interesting tests. I'm surprised KP is used though. According to Shimizu's FAST KP should only be used in greater sized shells because it doesn't accumulate the pressure that it can on such small scale...Or something along those lines (someone explain this to me). Swede, you might want to check if the stars are chlorate or perchlorate too.