Flash mixing

[Nessalco]

I mix my ball salutes using the binary method, but I do pre-screen 5 parts of Al into the perchlorate before filling the shell. I've tested the 70:5 mix with a blowtorch and a hammer - it will not ignite, and is insensitive to shock.

 

I'm just getting started making canister shells, and I'll need to mix flash in the open for the bottom shots. In the past when I've mixed flash openly I've used a combination of diapering and sifting. It goes very quickly, and reduces the time you have the comp exposed.

 

I do take necessary precautions - I mix only when the humidity is high (preferably a rainy day), use anti-static spray on myself and my (outdoor) work area, wear all cotton clothing, and work properly removed from all sources of ignition.

 

Kevin

[Maserface]

I always screen both chems seperate through about 60mesh, then diaper. But I have never needed to make more than 100g~ at a time.

 

If I were going to do more id get some anti static spray and have some water on the floor to increase the humidity and then screen away!

 

The way I see it, the risk doesn't get significantly higher with more, anything over a few grams going off in process and I think id wish I was dead. 100g or 5kilos.

[cogbarry]

Kevin,

I know you are very safety conscious because I've worked with you and have had in person conversations with you on this sort of subject. You're also a great worker, I missed you at Deerfield! I pretty much built that show (the club portion) by myself - ouch! I was sore for a week. I did have help loading and shooting it.

 

Maserface,

I agree with most of what you're saying but 100g's will ruin your day for sure. Humidity meters are cheap, so is water, you should be safe when working with all amounts, especially if your like me - more afraid of getting maimed than killed.

 

To both of you or everyone:

If you are screening flash, what are you using for screens? I don't think you need to use a fine mesh for mixing if your individual components have been screened through fine mesh or milled/ground, had cabosil added, 5% Al, etc. But is everyone using screens made of non-sparking material?

 

Like you, Kevin, I haven't been screening flash but now that I am making larger salutes for shows (if I could just buy them, I would), I have seen performance issues with the binary method. I have been using regular kitchen seives to mix star comps for a few years now. For now, I will go back to the diaper method (my variation of it) until I get some good screens. I know this method has worked very well in small devices.

[Nessalco]

Barry,

 

Sorry about Deerfield. One of the fellows who lives with me damn near died earlier that week, so my attention was on that.

 

I have wood-framed stainless steel screens I use for general work, but for making flash I dedicated a stainless steel strainer from wal-mart. It's about a 30-40 mesh screen, six inches in diameter. Because of how it's made you can't be sure you get it completely clean, which is why the screen dedicated to flash. I have several, for different purposes, with the use engraved on the handle.

 

You're right, I think, that using a coarser screen would work just fine once everything will pass that 40# screen.

 

Kevin

[cogbarry]

Barry,

 

Sorry about Deerfield. One of the fellows who lives with me damn near died earlier that week, so my attention was on that.

 

I have wood-framed stainless steel screens I use for general work, but for making flash I dedicated a stainless steel strainer from wal-mart. It's about a 30-40 mesh screen, six inches in diameter. Because of how it's made you can't be sure you get it completely clean, which is why the screen dedicated to flash. I have several, for different purposes, with the use engraved on the handle.

 

You're right, I think, that using a coarser screen would work just fine once everything will pass that 40# screen.

 

Kevin

 

No need to be sorry about Deerfield, that was a compliment, not a complaint. Also, nice tip on the WM screens. I'll look there. I really don't need a whole bunch of nested screens (although that would be nice), I just need one for mixing. I have a 100 mesh screen, star sizing and star making screens, coffee grinder for my oxidizers, several kitchen seives ranging from ~20 - ~40 mesh? I just don't think we should be screening flash with carbon steel mesh screens. Skylighter is out of stock of most screens, not to mention expensive. Some suppliers offer unframed screens but I'd rather spend my limited time making pyro, not tools. It must be nice to be retired, I'm not there yet.

[deepdixie]

I have only mixed flash using one method during the 10 years I have been involved in the hobby - the diapering method using a large sheet of precut Kraft paper. I tend to make multiple batches of small quantities, out of respect for and fear of the highly energetic material.

 

Each time I use a liberal amount of Static Guard anti-static spray, no matter if mixing during a period of low or high humidity. I spray my clothing and wooden work bench.

 

Someone raised a good question earlier that I hope one of the more experienced members could answer: What are the chances of accidential ignition by the friction caused by pressing in a tight fitting end cap or plug?

 

[dan999ification]

Depends on the flash used. I personally don't get it everywhere, it's possible to keep the plug end of the tube clean, it will help the glue stick

 

Dan.

[FlaMtnBkr]

If you are using 70/30 I would say the possibility of ignition is fairly low. If you are uncertain mix up s small batch of your chems and put some on a steel plate and hit with a hammer and scrape it around. If no reaction then I doubt cardboard will present a problem. You might need a piece of tape when hitting with a hammer to keep powder from flying everywhere.

 

Only reaction I have got was with chlorate and it was a faint smell of a burnt match. Don't remember if it also contained sulfur. I always do this when I question the sensitivity of a mix. A small pea size pile is all that is needed.

Edited November 23, 2013 by FlaMtnBkr

[Mumbles]

Unless you're making m-80s or the like, there isn't a whole lot of use for endplugs or caps. I certainly wouldn't trust them in mines or aerial shells. Using end disks (which rest on the walls of the tube), clay plugs, or tongue folded ends will greatly reduce any sort of friction.

 

In any case I wouldn't be too worried about 70/30 flash made with aluminum. When you start including components like sulfur, magnesium, or things that increase friction like antimony trisulfide, titanium, or even magnalium I would start to steer clear of things that need to be friction fit.