Purple Strobe pot

[optimus]

Name of composition: Optimus' Purple strobe pot v1

Composition Type: Irregular purple strobe

Creator: Optimus

Color/Effect: Purple / Violet

The Composition: (by weight)

 

Ammonium Perchlorate 4

Hexamine 4

Cu metal 2.4

Strontium Carbonate 0.5

Bind with NC (see prep notes)

 

Any Precautions/Incompatabilities: Copper reacts with AP. Unstable. Do not store. May be shock sensetive - treat with caution. Work outside when using NC and be wary of fumes when drying.

Precedure/Preparation: AP ground in pestle & mortar. 5g batch was bound with 1g NC lacquer. Cu metal is epoxy casting stuff from ebay.

 

Video at Pyrobin

 

The video is a 1/2" pellet of comp.

 

This is still a work in progress but I wanted to share where I'm up to. The idea was to formulate a strobe pot without Guanidine / Tetramethylammonium Nitrates or variations on the AP/MgAl/Mg strobes, making a relatively low light output, saturated strobe. This is not based on any particular comp or existing system.

 

It tends to extinguish itself without binding with NC. Strontium can be removed for a blue strobe. I would like to optimise the comp for use as microstars - I have a feeling upping the NC content might be worth trying as currently the stars are blowing out / not lighting properly.

 

I would appreciate feedback on this, as I said it's a work in progress and I don't have a massive amount of time for testing. I haven't tried different grades of Cu or tested it bound in tubes yet.

Edited February 10, 2011 by optimus

[Ralph]

looks cool purple strobes in the sky would be great

[Mumbles]

Have you ever tried the somewhat traditional purple strobes utilizing potassium sulfate as the secondary fuel and CuCO3 with SrCO3 as colorants? They still use magnesium of course.

 

The video you posted is by far the most vibrant purple strobe I've ever seen. I wonder if something could be done to stabilize the copper powder. A quick search brings up a few passivators. Benzotriazole, some vague references that chromates might work, and even citric acid. Benzotriazole while it may seem exotic, but it's a common anti-fog agent in photography. I've seen it available as a water treatment aid for swimming pools as well. Not extremely difficult to make either if you put your mind to it. I have no idea if it would be able to protect copper from the very corrosive AP though. It may work as a surface coating, or perhaps just added in minimal amounts to the composition.

 

I'd hope with the relatively non-aqueous environment of the NC, it'd be able to put off the corrosion for a while, perhaps longer with a passivating agent in there. My other idea was to add some parlon. Swede here showed that it could protect magnesium from AP, so why not Cu as well? Adding a bit, and binding with NC should hopefully be able to dissolve it enough that it coats everything.

 

There is a blub here about citric acid passivating the surface of copper. It was specifically in regard to copper disks used in radioactivity detection, but it's not science if you can't repurpose it for your own needs: http://majorana.pnl...._Hoppe_2006.pdf

 

A surface passivation step was required to prevent the reformation of oxides and control the IR emissivity of the copper. After testing ~30 passivation procedures[4], the preferred method for passivation was found to be room-temperature immersion in a 1% aqueous solution of citric acid. Cleaned copper parts are immediately immersed in the citric acid solution for up to several minutes. Excellent results have been achieved with this passivation step which was found to be made more resilient by baking 24 hours at 100ºC.

[optimus]

I've tried a few of the purple AP/Mg strobes but was never particularly impressed. Especially not in terms of using as a strobe pot (at 10m away at least) and as microstars, the colour saturation seems to drop off when you get too close.

 

My main intention is to make these suitable for use as microstars but I thought I'd start off with a working pot as the base.

 

Thanks for the suggestions about protecting the Cu. My next test will be to up the NC content to try and keep them burning as microstars. As an added bonus I figure if this increases the strobe rate to a shimmer, some parlon might help, being a flame retardant and all. I could be wrong, but we'll see. NC is pretty much uncharted territory for me, never really used it before.

 

The citric acid passivation is very interesting. If the parlon interferes with the effect I'll certainly think about giving it a try, doesn't look particularly hard to do either...

[Seymour]

I gave the composition a try with my precipitated copper metal (home made).

 

Unfortunately it did not strobe, though it was a very pretty purple. I suspect that my copper is too fine.

 

I'd love to try it with a coarser copper, I should look for the epoxy stuff.

[optimus]

I gave the composition a try with my precipitated copper metal (home made).

 

Unfortunately it did not strobe, though it was a very pretty purple. I suspect that my copper is too fine.

 

I'd love to try it with a coarser copper, I should look for the epoxy stuff.

 

You might get a strobe by lowering the Cu content, mabye not if it's very fine. I'm not sure of the mesh (mabye -200) of my stuff but it's the standard used for casting - allover ebay in the UK so shouldn't be too hard to find.

[shagaKahn]

Mumbles wrote:

 

> Have you ever tried the somewhat traditional purple strobes utilizing potassium sulfate as the secondary fuel and CuCO3 with SrCO3 as colorants?

> They still use magnesium of course.

 

Have searched for such a formula and the closest I can find to what you describe are violet star comps attributed to Shimizu or Bleser.

 

Mind sharing that formula--or pointing to it?

 

Thanx Mumz,

s

[Seymour]

Mumbles was referring to the rather common Ammonium perchlorate/sulfate/Magnesium type strobe.

 

Instead of colouring with Strontium, Calcium, Barium sulfate, ect, as the secontary oxidiser (I think Mumbles made a typo when he said "secondary fuel") and colourant, you use Potassium sulfate, since Potassium does not give off much colour, and the colour it does give off is lilac. Thus you have a blank canvas of sorts, to add paint to in the form of Copper and Strontium carbonates.

 

If you just look for Ammonium perchlorate, sulfate and Magnesium strobes, you should have much better luck. Potassium sulfate is not the most widely used sulfate in them.

[shagaKahn]

Thanx Seymour, that did it.

 

Hoping it's kosher to cross post this link to a video I did last night--since we're all into strobes on this thread.

 

Till my straight Mg powder arrives I was trying a variation on the Twinkling Green Star #2 (Shimizu) loaded into a strobe pot. Mg/Al instead of straight Mg:

 

http://tinyurl.com/5wdd8ju Fullscreen toggle on the right side of the play bar.

 

(You see why I call it Schizo-Strobe).

[optimus]

So, I was thinking:

 

http://farm4.static.flickr.com/3156/2861258618_520f99bbb0_z.jpg

 

The coloured pellets are green and red strobes. Definitely no metal fuel, and I remember them burning with what looked like a hexamine flame between flashes. They're not included in the packs available anymore which might suggest they used relatively toxic chems. A few more examples HERE and HERE seem to show ones which have sublimed away.

 

Don't s'pose anyone has ever seen reference to organic-fuelled strobes?

 

I've tried a few more very small tests using 50/50 AP/Hexamine as a base, then adding ~20 of various things:

Strontium Oxalate - slow burning with erratic strobing, and constant hexamine flame - similar to what I remember of the old strobe pellets.

Copper Oxychloride - very fast burning with no strobe whatsoever.

Copper Oxide - medium speed with erratic strobe, smouldering with no visible flame between flashes.

 

The test with Oxychloride was interesting, huge flame envelope and good colour, and very fast burning which I wasn't expecting.

 

EDIT: not sure about mixing AP and the oxalate... is this a bad idea?

Edited February 23, 2011 by optimus

[optimus]

So...

 

Did a few tests with Nitrates. Seems to help keep the mixture lit, still erratic strobing, but using Strontium Nitrate is promising - really nice almost-red purple colour. Potassium Nitrate, obviously not a good idea but the colour was great, for the first few seconds at least...

 

Barium Nitrate is next on the list. Hoping for a nice aqua

 

http://www.pyrobin.com/files/strobe_tests.mp4

[shagaKahn]

Well following that original formula to the letter (minus the Sr carbonate) all I get's a nice blue flame. No strobe.

 

You mention repeatedly that it's hard to keep it burning but I didn't experience that with my mix. Even testing a small lump of it as dry powder without the NC lacquer.

 

Only thing I can think is I'm not using actual hexamine but some ground up Esbit fuel which I was led to believe IS hexamine--but perhaps it has some extra ingredients that are interfering with the strobe?

[Atrey]

One idea:

 

treatment Cu powder by solution neutral silikon cement in Dichloromethane.

 

I use this protection for Fe powder oposition parafin.

 

There is (maybe) usuable for Cu betwen AP.

 

I am sorry for my English:))

[Algenco]

One idea:

 

treatment Cu powder by solution neutral silikon cement in Dichloromethane.

 

I use this protection for Fe powder oposition parafin.

 

There is (maybe) usuable for Cu betwen AP.

 

I am sorry for my English:))

 

 

you got your point across, better than I could do in a 2nd language

[Askenaz]

Have you ever tried the somewhat traditional purple strobes utilizing potassium sulfate as the secondary fuel and CuCO3 with SrCO3 as colorants? They still use magnesium of course.

 

The video you posted is by far the most vibrant purple strobe I've ever seen. I wonder if something could be done to stabilize the copper powder. A quick search brings up a few passivators. Benzotriazole, some vague references that chromates might work, and even citric acid. Benzotriazole while it may seem exotic, but it's a common anti-fog agent in photography. I've seen it available as a water treatment aid for swimming pools as well. Not extremely difficult to make either if you put your mind to it. I have no idea if it would be able to protect copper from the very corrosive AP though. It may work as a surface coating, or perhaps just added in minimal amounts to the composition.

 

I'd hope with the relatively non-aqueous environment of the NC, it'd be able to put off the corrosion for a while, perhaps longer with a passivating agent in there. My other idea was to add some parlon. Swede here showed that it could protect magnesium from AP, so why not Cu as well? Adding a bit, and binding with NC should hopefully be able to dissolve it enough that it coats everything.

 

There is a blub here about citric acid passivating the surface of copper. It was specifically in regard to copper disks used in radioactivity detection, but it's not science if you can't repurpose it for your own needs: http://majorana.pnl...._Hoppe_2006.pdf

 

A surface passivation step was required to prevent the reformation of oxides and control the IR emissivity of the copper. After testing ~30 passivation procedures[4], the preferred method for passivation was found to be room-temperature immersion in a 1% aqueous solution of citric acid. Cleaned copper parts are immediately immersed in the citric acid solution for up to several minutes. Excellent results have been achieved with this passivation step which was found to be made more resilient by baking 24 hours at 100ºC.

thanks for the support, my English is not good, but I'm interested how much parlon must be added to a kilo of magnesium ?. I've used potassium dichromate with acetone. but I want to use parlon.