Dreaded "flash" question.

[BillyBobBodean]

I have been in pyro for the last 4 years, have built many 3" and 4" shells. I mill my own BP with willow charcoal and have had great results. I have read up extensively through APC and other pyro sites and I still have questions about flash powder, I see so many differing opinions, and am hoping the experts can weigh in. I have 3 oz. of Eckart 5413H aluminum powder, and KCLO4. I plan on making 10 grams or less of flash at a time. I have PPE, anti-static spray, and definitely observe all safety precautions. I will be using the diaper method to mix the flash. Questions I have:

 

1. Once mixed, what is the best container to store this in (I have a magazine), just wondering about the small batches. Plastic containers OK?

 

2. One use I have in mind is to make small reports out of vinyl cap plugs, filling the plugs and then inserting a small piece of time fuse. Any danger (friction) when installing fuse?

 

3. The other use is to help break small 1.75 " shells, by adding a gram or two to the BP break charge. My concern is the friction inside the shell when I close and tape (ball shells), or spike can shells.

 

Sorry for the long post. I have found so much helpful info on APC and respect your opinions.

 

 

 

[ddewees]

10 grams won't last very long.

[nater]

1. Don't store loose flash. Make as much as you will use for building in one session, complete the devices and store them appropriately.

 

2. Use a tiny funnel so the flash powder does not get on the sides of the cap plugs.

 

3. The safest means is to use a flash bag tied to the end of your time fuse or spolette. Many, many shells are made with the break charge dusted in flash or a little sprinkled on top. Be careful when closing shells, treat them gently and it won't be a problem. Consider that the report must survive the forces of being lifted and if they are inserts, the break as well. Also consider cases of shells get treated rough during shipping and storage without being set off. Don't be casual with them because salutes are dangerous, but standard flash won't ignite if you sneeze on it or look at it cross-eyed either.

Edited April 11, 2015 by nater

[BillyBobBodean]

Thanks nater, your input helps a lot!

[nater]

10 grams won't last very long.

That is 1 or 2 headers for a 1/4" bottle rocket for me.

[OblivionFall]

1g Is quite a lot for a 1.75" Shell. I would consider 0.5g

[schroedinger]

Like oblivion pointed out 1 g for 1.75" is quite a lot, a 3" will most times use just 1-1.5g for boosting.

 

To #1

Use up your whole made flash in one session. If you have fladh left over, just grab a cap plug and a preparred TF and fill them up until the flash is gone.

[GreginCA]

As was stated above, friction is not much of an issue with standard 70/30 flash. I have personally done many impact tests on this formula and find it rather difficult to ignite with solid blows of a 16 oz smooth face hammer with the flash sitting on a 3/4" steel plate.

 

On the other hand, static electricity is a problem! Any time you are working with flash powder you need to remove/ground out all sources of static electricity in your work area. Static spray, wrist ground (as used to work on PC's), cotton or other static resistant clothing, etc. You want a full face shield and a dust respirator and long sleeved shirt. Then there is the mixing process. There are a number of ways to mix flash, some safer than others. The diaper method is probably the most common and recommended for mixing most flash compositions. Some folks mix it in a plastic baggie, but that makes me a little nervous unless the baggie is a special anti-static type... but that's just me. For a small 10 gram batch, I put the milled oxidizer and fuel together in a 3 oz paper Dixie cup, then take a second Dixie cup and place it upside down on the cup containing the composition. Use some masking tape and seal the two cups together. Then I gently tumble the mixture until it is well incorporated. I like this method for small batches because it self contains any aluminum dust and eliminates most any static build up.

 

70/30 Flash is not a monster death mix, but is something one needs to treat with respect. Before you mix flash of any kind, you need to understand why it does what it does. If you understand this then it is well within your ability to mix it with very little likelihood it will accidently ignite. If you do not fully comprehend it's chemical and physical properties, then you are literally playing with a potential disaster.

 

DO NOT STORE FLASH! PERIOD, THE END!

[schroedinger]

For a 10 gramm batch use the diaper method, it is fast and also creates nearly no friction and dust, i don't see any advance in the method described by Gregin, but a lot more of friction.

 

Also if you make devices that contain 10g or more as a report, read up on the binary mixing method.

[Wiley]

How is there any more friction involved with that method? It's just the binary method but you're opening the container back up. Some people who build big shells screen their flash by shaking the composition through the screen. You don't want to rub it through for obvious reasons.

[BillyBobBodean]

1g Is quite a lot for a 1.75" Shell. I would consider 0.5g

Thanks! That's great info and that's what I will do!

[BillyBobBodean]

Thanks all, this is why I come here often, great info!

[mikeee]

Cardboard tube with a couple of end caps, lightly shake the 70/30 back and forth inside the tube.

Have used this method for rocket headers for years with no problem.

Leave about 1/2 of tube empty so the materials will easily mix.

You could always attach a handle to the tube if you don't want the comp close to your hand while mixing.

When mixing flash in a rocket header I usually hold the rocket stick while shaking it back and forth.

[GreginCA]

As stated by Wiley and Mikeee, the process I described is simply a variation of the binary mixing method and is actually safer than diapering it right in front of your face in my humble opinion. If particle impact were an issue with this mix then it would be far too unstable to be launched out of a mortar. As I stated above, I have personally conducted scores of impact tests on the 70/30 mix using all various combinations of Old School Swedish Perc, Domestic Perc, Chinese Perc, Old School Echart (Honest to goodness 1970's) Blackhead Aluminum, Echart 5413 H Super Aluminum, Star Molecule Aluminum and Indian Aluminum with virtually no variation in impact sensitivity. To elaborate on what Wiley stated, most if not all commercial fireworks manufacturers in the United States actually screen their flash. Can you visualize diapering 10 lbs as is a common batch size in commercial manufacturing? I also like mikeee's variant utilizing cardboard tubes with end caps. I might try that for a larger batch next time I make a few 3" salutes/bottom shots. The reason I like the 3oz Dixie cups for 10 to 30 gram batches is the expediency/improved incorporation and I always have Dixie cups/masking tape on hand :-). Lloyd Sponeneburgh and I had a conversation about flash sensitivity a few years ago and he shared a lot of his own insights/finding on quite a few different flash formulations. As long as you stick to the 70/30 formulation, it is not all that impact sensitive folks. Start talking about Mg fuels and you enter an entirely new set of parameters!!!

Edited April 12, 2015 by GreginCA

[ddewees]

40 mesh brass screen onto paper. Make sure your chemicals are free of lumps first.

[countryboy7978]

Grind 70/30 in a mortar and pestle and it will ignite (proven fact). Spill it on a gravel surface and step through it and it may very well ignite(PGI accident 2004). The hammer test doesn't tell all as it mainly tests impact vs friction.

 

If you watch Albert at Little Big Shots make flash, he does screen it. He also uses sulfur in his mix. Diaper is great for small batches but once you get to 1lb or more then it becomes less desirable. The chemicals don't get mixed as intimately as we like and spills are more likely to occur. Most accidents believe it or not have been linked to poor housekeeping (not cleaning up spills immediately)

[Nessalco]

Two words - TPA

 

KO

[BillyBobBodean]

Two words - TPA

 

KO

I'm sorry, I don't understand!?

[FlaMtnBkr]

Terephthalic acid. If you do a search you will find a lot of info I and a couple others have posted over the last few years.

 

It makes a "safe" flash that burns slower than many star comps when unconfined. But when confined it acts like regular 70/30 and actually a little more powerful. It also works in small amounts and doesn't need a primed fuse unlike blue aluminum. Blue aluminum is safer as it just doesn't burn unconfined. But confined and with a hot primed fuse it lights. However, it needs at least 10-12g so not good for smaller inserts like cap plugs.

[BillyBobBodean]

Thanks FlaMtnBkr, I will research!!

[BillyBobBodean]

Terephthalic acid. If you do a search you will find a lot of info I and a couple others have posted over the last few years.

 

It makes a "safe" flash that burns slower than many star comps when unconfined. But when confined it acts like regular 70/30 and actually a little more powerful. It also works in small amounts and doesn't need a primed fuse unlike blue aluminum. Blue aluminum is safer as it just doesn't burn unconfined. But confined and with a hot primed fuse it lights. However, it needs at least 10-12g so not good for smaller inserts like cap plugs.

I've done some research and have read your posts, sounds like something I would like to try. I did an ebay search and found a few suppliers, I don't need a large quantity. Is this acceptable in your opinion? Thanks for the help!!!

 

Terephthalic Acid 100 g poly bottle chemically pure

Cas: 100-21-0

[FlaMtnBkr]

I don't see that listing. How much is it with shipping?

 

TPA is used on the order of like 30-40 million tons a year but only has a few purposes so minimum quantities are usually on the order of a rail car. So it's not real easy to find outside of industry or in small amounts.

 

I use the formula 71-17-12 perc, aluminum, TPA. In that ratio a 100g of TPA will make around 1.8 lbs of flash so is plenty to experiment with. I don't know how expensive it is but if it's around $10 with shipping that isn't terrible. Another source is Cracker assuming he still has some but he has been MIA for the last 6 months or more.

 

It's pretty neat though. 20g in a paper cup with a fuse going through the side took 8-9 seconds to burn. Versus the near instant intense flash of heat and light that regular stuff does. But when a couple grams are put in a 1/32" wall tube it makes a thump that can be felt in the chest. I've tried quite a few different formulas and none give that feeling against the chest in those small amounts. Anyways, nothing in this hobby is without risk but this seems like it should make working with flash quite a bit safer when working with It before it's contained in a shell. In my opinion at least.

[Nessalco]

Fla, I'm sold on the stuff. There are a couple of other advantages besides the burn rate. The compound is less sensitive to friction and static than other flash compounds, especially if you granulate it as described in the original patent. Also, the granulated comp doesn't tend to settle, so there is no need for rice hulls or other fluffers. The open burn rate for the granulated comp is even slower than the raw powder. TPA flash is cheaper to produce than other types, since you are replacing the most expensive component (Al) with TPA.

 

There are a couple drawbacks. The light output is reduced as the proportion of aluminum decreases. It does require adequate containment. Cap plugs are marginal - the manufacturing variations leave some thinner than others, and the thinner ones do not adequately contain the charge. I haven't gotten it to work at all in crosetttes. It works fine in paper tubes with glued in plugs.

 

I treat it like I'd treat black powder, though the open burn rate is much slower than BP.

 

Kevin

[Nessalco]

PS> There is a deal in the works for a reliable vendor to supply TPA in hobby amounts. Once it's publicly announced I'll make sure folks here know.

 

KO

[nater]

^^

 

It is getting very close! I spoke with this vendor a few days ago, nobody will have to wait too much longer.