Flash Safety - Bill Ofca on Flash

[fredhappy]

Yes, indeed I ve noticed quite a number of stars being blown blind with the flashbags. I guess that corresponds with what you are saying.

 

I will try slowflash. I just like 70/30 pot perc/dark al flash , but I also respect it very much. Just the right amount will give real nice big breaks, cut down substantially on pasting, and give that lovely kaboom we all love so much. It is a great mixture, but unfortunately in case of an accident very catastrophic stuff.

 

Every bit of information from pro's about relatively "safe" flash handling can contribute to a more safer practise in my opinion.

 

Thanks a million for your answer Bill, it clarified some stuff that was on my mind for a long time. I really appreciate.

 

friendly pyro greetings,

[billofca]

I cant find fault with your method Bill but I am wondering why the cotton gloves while screening the perc? It has a flammability rating of 0 on my MSDS and needs a fuel to burn. Also, it is an irritant to the skin so I use nitrile gloves.

 

I do like the reminder to use a cardboard box but the use of an anti static bag is fine as well. I use the antistatic pink bags from Uline.

 

No special reason for cotton gloves except that your hands don't sweat while wearing them for long periods, they are comfortable, and they were available. Its just a P.S. that they don't generate static when handling any fireworks comps. Nitrile gloves may be better in the sense that cotton weave gets impregnated with chemicals.

[billofca]

Sorry Bill, the only Potassium Crystal that is a piezo generator is Potassium Niobate (KNbO₃), but since tendons, bone and silk do have piezo tenancies, perhaps your tests of whole crystals would yield and electrical charge.

 

Okay, I presume you are a chemist and know this for sure? Do you think what I described was due to tribo-electric charging of static electricity? That was my other thought of a possibility that explained the phenomenon. (I am a retired electrical engineer). Perhaps the charge field was collected off the plastic bag liner by the outside steel drum and the spark jumped from the drum lid rim to the scoop. I can't help but be curious about this because I did not feel any static shock when I removed the steel lid to enter the drum of perchlorate. There was no spark when I introduced the aluminum scoop into the drum. It was only after hard and repeated stabbing at the hardened cake of perchlorate that I saw this huge snapping blue spark when I withdrew a full scoop of the perchlorate and the scoop passed by close to the drum lid-rim. I am open to any reasonable discussion to explain what I experienced. Thanks for your input.

[dagabu]

Okay, I presume you are a chemist and know this for sure? Do you think what I described was due to tribo-electric charging of static electricity? That was my other thought of a possibility that explained the phenomenon. (I am a retired electrical engineer). Perhaps the charge field was collected off the plastic bag liner by the outside steel drum and the spark jumped from the drum lid rim to the scoop. I can't help but be curious about this because I did not feel any static shock when I removed the steel lid to enter the drum of perchlorate. There was no spark when I introduced the aluminum scoop into the drum. It was only after hard and repeated stabbing at the hardened cake of perchlorate that I saw this huge snapping blue spark when I withdrew a full scoop of the perchlorate and the scoop passed by close to the drum lid-rim. I am open to any reasonable discussion to explain what I experienced. Thanks for your input.

 

Good lord no Bill, I Am a jack of all trades, master of none but I do know who to ask when I have questions. I have an associate that works at Medtronic in R&D that has his doctorate in electrical engineering /computational science. He is a bastion of knowledge though you need a dictionary and about four hours spare time to get a straight answer from the guy.

 

One of the devices they have been researching is piezoelectric powered and reads blood pressure in real time 24/7 so when you asked the question, I shot it to him and he laughed at me for my presumption that there would be enough voltage built up by hand pressing to make a spark. His assumption was therefore that the crystals were generating static electricity as you had said earlier.

 

frankly, I have no clue but in making whistle mix this morning I also had to break clumps with an aluminum scoop but did not see any evidence of a spark when grounding the scoop.

 

Go figure.

[WSM]

Yes, indeed I ve noticed quite a number of stars being blown blind with the flashbags. I guess that corresponds with what you are saying.

 

I will try slowflash. I just like 70/30 pot perc/dark al flash , but I also respect it very much. Just the right amount will give real nice big breaks, cut down substantially on pasting, and give that lovely kaboom we all love so much. It is a great mixture, but unfortunately in case of an accident very catastrophic stuff.

 

Every bit of information from pro's about relatively "safe" flash handling can contribute to a more safer practise in my opinion.

 

Thanks a million for your answer Bill, it clarified some stuff that was on my mind for a long time. I really appreciate.

 

friendly pyro greetings,

 

 

When boosting burst (yeah, say that ten times fast) with flash it's best if you prime the stars with a thick (say 0.040" minimum or more) and very hot prime which contains a large amount of charcoal (~20%) and has a rough surface when dry. More suface area means a better chance to catch a spark and more charcoal means a better chance to hold that spark till the star slows down enough to ignite!

 

I haven't built a shell in a long time, BUT when I did and boosted the burst; I saw a dramatic improvement when I used the hot prime layered thick on my stars (>90% ignition!) and a whole lot fewer blind stars. If you're really clever, use the same composition for your prime and burst (I wish I had thought of that, but I heard it from a pro a long time ago).

 

Speaking of pros, the safest method I've seen for making flash inserts commercially involved separate sized scoops for perchlorate and dark aluminum and filling the prepared paper casings with the separate components, then rolling the closed casings down little wooden ramps to mix the contents inside. After all this the inserts were built into the shells. They worked flawlessly and cut out the hazards of personally mixing and handling flash. I think the perchlorate was freshly milled which made it sort of fluffy and aided in the mixing stage. The old timers used to put a small compatible star in with the flash in the salutes to help with the mixing.

 

For what it's worth...

 

WSM

Edited November 2, 2010 by WSM

[dagabu]

The old timers used to put a small compatible star in with the flash in the salutes to help with the mixing.

WSM

 

Hmmm, you know, I think I remember seeing a brief hint of color from time to time in some smaller reports. Think the star was what was contributing to that or did the the star just shatter?

-d

[WSM]

Hmmm, you know, I think I remember seeing a brief hint of color from time to time in some smaller reports. Think the star was what was contributing to that or did the the star just shatter?

-d

 

Quite possibly a bit of both. A star of bound perchlorate and bright aluminum wouldn't leave a color signature (and you wouldn't have to bother with prime either).

 

WSM

[dagabu]

That's pretty cool! Thanks for sharing, I think I will make a small batch of "mixing stars" for bottom shots.

 

-D

[fredhappy]

When boosting burst (yeah, say that ten times fast) with flash it's best if you prime the stars with a thick (say 0.040" minimum or more) and very hot prime which contains a large amount of charcoal (~20%) and has a rough surface when dry. More suface area means a better chance to catch a spark and more charcoal means a better chance to hold that spark till the star slows down enough to ignite!

 

 

My prime has 18 percent charcoal. It doesn't burn too quickly, I don't mill it as long as my meal powder. I also add a few percent Mg/Al and silicon powder. The silicon should roughen it up a bit too. I guess I just didn't apply enough prime to my stars. I'll start experimenting without the flashbags and just dump the flashpowder on my ricehulls. I've made some new batches of stars and they are thickly primed, so I expect to see some improvement . I closed a 5 incher today, and I did feel somewhat uneasy having just dumped the flashpowder on the ricehulls.

I guess gently does it...

Thanks for your information and reply.

Edited November 2, 2010 by fredhappy

[WSM]

My prime has 18 percent charcoal. It doesn't burn too quickly, I don't mill it as long as my meal powder. I also add a few percent Mg/Al and silicon powder. The silicon should roughen it up a bit too. I guess I just didn't apply enough prime to my stars. I'll start experimenting without the flashbags and just dump the flashpowder on my ricehulls. I've made some new batches of stars and they are thickly primed, so I expect to see some improvement . I closed a 5 incher today, and I did feel somewhat uneasy having just dumped the flashpowder on the ricehulls.

I guess gently does it...

Thanks for your information and reply.

 

Hi Fred,

 

For more "texture" on star prime, some folks have added 4%-5% wood flour in the prime and gotten a very nice rough surface when it dries. Another technique I've heard of is "dusting" the freshly primed stars with fine grain powder, like 4Fg or 7Fa. I've used the wood flour technique successfully but feel the grain powder method is a little too pricey for my tastes. Have fun.

 

WSM

[cogbarry]

I think static is normally the factor that people tend to shy away from that make that method unpopular. It is actually commonly done on much larger scales in commercial manufacturing. 200lbs at a time in a modified cement mixer remotely. If you can get an area far enough away from anything else it may be useful, but without that it's exceedingly dangerous.

 

FYI, it is going to go up like a bomb if it does go off, because that is essentially what it is. A jar, no matter how loose the lid is will be enough to self confine it.

 

I'm guessing that a question here will cause this thread to move up?

 

I keep reading about the binary method for making salutes. However, could the aluminum inside a closed ball shell not generate static while the shell was being pasted? This doesn't seem to far from the comp being rotated in a mill jar.

[cogbarry]

I'm guessing that a question here will cause this thread to move up?

 

I keep reading about the binary method for making salutes. However, could the aluminum inside a closed ball shell not generate static while the shell was being pasted? This doesn't seem to far from the comp being rotated in a mill jar.

 

I should specify a mill jar without media.

[Algenco]

I should specify a mill jar without media.

 

 

it wouldn't matter if it did generate static inside the ball, where's it going to go?

No danger unless a spark is generated

[cogbarry]

it wouldn't matter if it did generate static inside the ball, where's it going to go?

No danger unless a spark is generated

 

Thanks. I was hoping that was the case. From working with ESD sensitive electronics occasionally, I'm aware that you can drag your stocking feet across a shag rug on a dry winter day with a sensitive part. It isn't until you discharge into/through the part that you're going to fry it. However, I wasn't sure that the aluminum inside the shell couldn't somehow create a spark. Of course it's a non-ferrous metal and doesn't spark does it.

[dagabu]

It sounds like you have two subjects mixed together, static sparks and mechanical sparks. Static: Take for instance a Leyden jar, it stores a static charge inside of it but even if you had a flammable gas inside the jar, the gas would not be ignited by the storage of the charge within the jar.

 

The ball mill is the same, it will definitely create a static charge but since it cannot go "to ground" no spark is created.

 

"Mechanical sparks occur when there is excessive friction between metals or extremely hard substances. As the two substances rub against each other, small particles are torn off the surfaces. This tearing is due to the large amount of friction. For a metal to spark, it must satisfy three conditions:

 

• The energy, which supplies the tearing off of the particles, must be sufficient to heat the metal to high temperatures. Softer metals usually deform before they spark.

• The metal must be able to oxidize and burn easily. Generally, a metal’s sparking temperature is the same as its burning temperature.

• The metal’s specific heat is the last factor. A metal with a low specific heat will reach a higher temperature for the same amount of energy input."

-Source

 

 

[cogbarry]

It sounds like you have two subjects mixed together, static sparks and mechanical sparks. Static: Take for instance a Leyden jar, it stores a static charge inside of it but even if you had a flammable gas inside the jar, the gas would not be ignited by the storage of the charge within the jar.

 

The ball mill is the same, it will definitely create a static charge but since it cannot go "to ground" no spark is created.

 

"Mechanical sparks occur when there is excessive friction between metals or extremely hard substances. As the two substances rub against each other, small particles are torn off the surfaces. This tearing is due to the large amount of friction. For a metal to spark, it must satisfy three conditions:

 

• The energy, which supplies the tearing off of the particles, must be sufficient to heat the metal to high temperatures. Softer metals usually deform before they spark.

• The metal must be able to oxidize and burn easily. Generally, a metal's sparking temperature is the same as its burning temperature.

• The metal's specific heat is the last factor. A metal with a low specific heat will reach a higher temperature for the same amount of energy input."

-Source

 

 

Good explanation and thanks for the source link as well. Aluminum is quite soft and as a former machinist I know that quite well. It is very easy to cut,drill,etc. I know it has a relatively low melting temp compared to say steel (as a former welder I know that) . I suppose the ignition in the ball mill example would be most likely to occur when one opens the jar and somehow allows the built up static to reach ground. Of course, I'm not sure why anyone would want to mill two fine powders together that only need to be mixed. It seems it would actually be more laborous than simple diapering.

 

One note regarding static as an IT person (current occupation): I never wear a wrist strap, not that it isn't a good idea but I have developed the habbit of always grabbing the chassis of a system with one hand before touching any parts with the other. I have never ruined a part with ESD. I've often thought about this situation in the inverse, if the part has a charge and I'm grounded, I suppose the part could dishcharge through me if I were to touch it. Seems to me it's a good idea to have your work bench grounded and get in the habbit of touching the bench before touching a device or comp that is ESD sensitive and that is sitting on the bench.

 

In any case, thank you all for the feedback. I keep reading about all the accidents in the safety topic and it makes me think twice and to seek advice from those more knowledgable and/or experienced. It also makes me all the more serious about covering all the legal bases in case anything ever did happen.

[dagabu]

Of course, I'm not sure why anyone would want to mill two fine powders together that only need to be mixed. It seems it would actually be more laborous than simple diapering.

 

I regress, I was not speaking at all about flash, it should NEVER be milled, ever! The point I was making was only regarding the creation of the charge and yes, if you "ground" the contents of the jar you may indeed create a spark. BOOM!

 

-dag

[cogbarry]

I regress, I was not speaking at all about flash, it should NEVER be milled, ever! The point I was making was only regarding the creation of the charge and yes, if you "ground" the contents of the jar you may indeed create a spark. BOOM!

 

-dag

 

I was certainly not suggesting this either, no no! But someone asked this question earlier on in this thread. He/she was wondering why it couldn't be done without media. One of you (Mumbles I think?) responded to this idea and mentioned that friction was one reason not to.

 

My question in this context was one of concern. I keep reading/hearing about the binary method and I thought that pasting a salute would also result in the comp being rolled around inside the shell, sliding against the insides, creating static. I wanted to confirm my thoughts/hope that there was no danger from this as there is no way for an ESD to occur.

Edited April 27, 2011 by cogbarry

[fredhappy]

I was certainly not suggesting this either, no no! But someone asked this question earlier on in this thread. He/she was wondering why it couldn't be done without media. One of you (Mumbles I think?) responded to this idea and mentioned that friction was one reason not to.

 

My question in this context was one of concern. I keep reading/hearing about the binary method and I thought that pasting a salute would also result in the comp being rolled around inside the shell, sliding against the insides, creating static. I wanted to confirm my thoughts/hope that there was no danger from this as there is no way for an ESD discharge to occur.

 

You have to take into account that with the binary method you also add some dry ricehulls to aid with the mixing. This also dampens the movement inside the closed ball shell a bit. I really like this way of mixing salutes, not once is there any flashpowder in the open when you are making them. I settle for the fact that these salutes can hold less flash powder as opposed to filling them to the brim with diapered flash. 60 grams is an incredibly loud thump , loud enough for my usual taste. A 3" binary mixed salute can hold about 60 to 70 grams.

Edited April 27, 2011 by fredhappy

[dagabu]

You have to take into account that with the binary method you also add some dry ricehulls to aid with the mixing. This also dampens the movement inside the closed ball shell a bit. I really like this way of mixing salutes, not once is there any flashpowder in the open when you are making them. I settle for the fact that these salutes can hold less flash powder as opposed to filling them to the brim with diapered flash. 60 grams is an incredibly loud thump , loud enough for my usual taste. A 3" binary mixed salute can hold about 60 to 70 grams.

 

?????????

 

Fred, I dont know anyone at PGI that adds rice hulls to binary mix in a rocket tube body for a end-of-flight salute. In fact, I dont know of a commercial American manufacturer that uses fillers with flash. Heavy walls and confinement are the key.

 

-dag

[FREAKYDUTCHMEN]

?????????

 

Fred, I dont know anyone at PGI that adds rice hulls to binary mix in a rocket tube body for a end-of-flight salute. In fact, I dont know of a commercial American manufacturer that uses fillers with flash. Heavy walls and confinement are the key.

 

-dag

 

So what?

 

Heavy walls and confinement... well I don't think so, not for any type of flash.

[dagabu]

So what?

 

Heavy walls and confinement... well I don't think so, not for any type of flash.

 

Care to wager on it Freaky?

 

-dag

[Mumbles]

I can't say I've seen anyone personally add rice hulls or a bulker to their binary mixed flash salutes. I've certainly seen it done with pre-mixed flash though. It may be done with imported salutes as well. I do not recall if the one I saw opened up was commercial, or homemade. It's a way to cheapen the devices. Less comp, more profit.

 

I try not to associate myself with you odd rocket types , so it very could be done for all I know. I prefer a solidly packed canister salute myself.

[cogbarry]

I can't say I've seen anyone personally add rice hulls or a bulker to their binary mixed flash salutes. I've certainly seen it done with pre-mixed flash though. It may be done with imported salutes as well. I do not recall if the one I saw opened up was commercial, or homemade. It's a way to cheapen the devices. Less comp, more profit.

 

I try not to associate myself with you odd rocket types , so it very could be done for all I know. I prefer a solidly packed canister salute myself.

 

Wow, look what I started! I wasn't trying to get a big flash thread going. Just wanted to get some more safety education on it regarding that specific question on friction. However..... I was actually wondering about the rice hulls myself. I made a couple salutes with the binary method and used rice hulls as a temporary barrier between the two chems. Probably not a necessary step (how much surface area contact is there after simply dropping on on top of the other?) I did not fill the shells but you can easily go way beyond half capacity with a heaping mound on one hemi and still have the ease of closing with one empty half. I would think hulls or not, after pasting the shell it would be mixed almost as thoroughly as pre-mixing. I also know that some of my more experienced friends use this method. From what I've heard, it's the only allowed method at certain clubs such as the PGI. In any case, it would be great if I could just buy salutes, save myself the danger of making my own, allow a machine to make them instead, and use my time learning the much more challenging skills of color shells, double petals, different effects such as crackling stars, etc. Haven't thought too much about rockets yet. Is there anything I should know about "rocket types"?

 

I might add that although I have the utmost respect.... I'm not afraid when pasting a color shell, actually enjoy it. But as a fireworks spectator/fan, what the hell are these wimpy shows without salutes!

Edited April 27, 2011 by cogbarry

[fredhappy]

?????????

 

Fred, I dont know anyone at PGI that adds rice hulls to binary mix in a rocket tube body for a end-of-flight salute. In fact, I dont know of a commercial American manufacturer that uses fillers with flash. Heavy walls and confinement are the key.

 

-dag

 

OK, it depends I think. With standard 70 30 pot perc/ dark al, not much confinement is needed. It is another story when you use KNO3 slowflash type of mixtures, those flashes need confinement. I only use 70 30.

 

Adding ricehulls really helps with the mixing. I just use some uncoated ricehulls for the sole reason of aiding the mixing. 70/30 flash tends to form a big lump in the binary salutes when you leave out the ricehulls.You can actually feel it lumping in there when you turn the salute up side down for instance. Adding ricehulls helps keep it more free flowing. It won't do any harm either, nor give problems with static or friction. I was given this advice by a very experienced fellow pyro, and found that it improved the binary mixing.