27 replies to this topic

[mshaner]

heres a composition i found in a database im not sure how well it works as ive never tried it but if you can get the chems u can give it a go

Electric Match
Source: PML, post by Mike Carter <pyro@primenet.com
Comments: This composition does not require the use of a bridge wire. The composition itself acts as a resistor. Comments from the poster: "The matches fire just fine on 200 feet of #16 guage wire and a standard 12V battery two at a time. Sometimes there's a delay...I haven't tested these on the high power electric firing systems so I don't know how they fare."
Preparation: 1) Bind in water. Make CMC & Water into a mostly soupy mess. Add components into a container and mix well. 2) Dip freshly stripped wire with both conductors about 1mm or slightly less between them, evenly parallel. The longer the exposed metal on the wire, the less Ohmage the match will have. Allow to dry in vertical hanging position. Redip as necessary. I find that two dips is just fine. 3) Once the comp is dry, you will need to coat it with NC (Nitrocellulose) laquer. I find that two dips in the NC laquer is enough to keep the very brittle comp from cracking or splitting while manuevering the wire into your shell or mine or rocket motor. I normally will color the double-dippers with some Iron Oxide stirred into the NC Laquer so I have a visual that they're unsuitable for firing whistle motors. (Double Dipped tend to go BANG, and destroy the motor).
Potassium chlorate, Ball milled into a fine powder.....16
Conductive lampblack..............................3
Magnalium (50/50), 200 mesh.......................3
Atomized aluminum, 120 mesh.......................2
Zirconium, 200 mesh (optional)....................2
CMC Binder (carboxymethylcellulose)...............5

Its been a long time since the string has been addressed, but that's just how busy life is sometimes

Disclosure: I'm an Rocketry EXer and have a good foundation of experience in the department of formulations, but I am still teachable.

That being said, the above formulation's numbers don't "add up" do they? What am I missing?

Thanks for the help

[karlfoxman]

They will be expressed in parts, not percentages. There is good explination HERE from a few well respected guys.

[mshaner]

They will be expressed in parts, not percentages. There is good explination HERE from a few well respected guys.

Doh! Missed that "part"

I don't have formulations written in this format. Oddly enough, the referred to post was one of the first post I read in this forum and BigG has always been a big help to me.

Thanks again,

Shane

[cat]

Potassium chlorate, Ball milled into a fine powder.....16
Conductive lampblack..............................3
Magnalium (50/50), 200 mesh.......................3
Atomized aluminum, 120 mesh.......................2
Zirconium, 200 mesh (optional)....................2
CMC Binder (carboxymethylcellulose)...............5

Just some quick notes for anyone interested in using this formula The Mg needs to be coated Zr doesn?t play nice with water activated binders like CMC. I?ve made this formula twice the first with CMC and it was quite apparent that the metals very quickly corroded. The second with NC worked quite well. This was intended to be a conductive dip but never worked out that way for me the resistance was far too high for what I?d planed on using it for. It should probably be said that the above formula will be friction sensitive. As for conductive dips sensitized dark flash <formula omitted> with addition of 20-30% carbon micro spheres worked well.

-Cat

[alany]

I started with a similar exotic pyrogen, but ran into corrosion problems in long-term storage.

I've settled on the old "dark report" 1:1 Potassium Chlorate, Antimony Trisulfide for bridged matches with NC binding. I just coat over it with a universal prime to make it safer for contact with other compositions.

[Plays with Fire]

Hey, I just tested my first electric match today. It was made by cutting one stand of a 2-ply speaker wire 2cm shorter than the other, and soldering a short length of nichrome between them, as so no more space was taken up than was by the uncut wire. Upon a dry run (no composition) with a 6-volt battery, the nichrome turned red hot then broke with a spark, as expected. After coating the match in a mix of NC lacquer (I cut up ping-pong balls and dissolved them in acetone) and meal powder, then recoating it in the same mixture, I let it dry and then tested it with the same 6-volt battery. The side of the match that was the nichrome burned/sparkled somewhat but was really unimpressive, but the other wire of the 2-ply that was coated as well (same coat, one dip for both as they are literally touching) didn't burn!

As you can imagine I was quite disappointed Now, I want to know why the composition didn't completely ignite both sides, as they're not only literally touching, they were coated together! I think maybe the NC Lacquer + Meal Powder mixture wasn't flammable enough, and didn't burn hot enough to spread the ignition throughout, and so only the comp directly touching the *hot* nichrome could be ignited? Please, help me

Thanks much,
Plays with Fire

[RegimentalPyro]

Hey, I just tested my first electric match today. It was made by cutting one stand of a 2-ply speaker wire 2cm shorter than the other, and soldering a short length of nichrome between them, as so no more space was taken up than was by the uncut wire. Upon a dry run (no composition) with a 6-volt battery, the nichrome turned red hot then broke with a spark, as expected. After coating the match in a mix of NC lacquer (I cut up ping-pong balls and dissolved them in acetone) and meal powder, then recoating it in the same mixture, I let it dry and then tested it with the same 6-volt battery. The side of the match that was the nichrome burned/sparkled somewhat but was really unimpressive, but the other wire of the 2-ply that was coated as well (same coat, one dip for both as they are literally touching) didn't burn!

As you can imagine I was quite disappointed Now, I want to know why the composition didn't completely ignite both sides, as they're not only literally touching, they were coated together! I think maybe the NC Lacquer + Meal Powder mixture wasn't flammable enough, and didn't burn hot enough to spread the ignition throughout, and so only the comp directly touching the *hot* nichrome could be ignited? Please, help me

Thanks much,
Plays with Fire

Dip first with a slurry made of good BP meal +5%dextrin, using water/meths (50:50) as the solvent.

You can add some [2-5%] fine pyro metals [Al, Ti, Mgal] to generate lots of hot sparks. Make sure the metals are coated so that they don't react adversly with water! Silica has also been used to good effect here.

Once this has dried off then dip with NC lacquer to make waterproof. Should ignite with a sharp crack every time

[Plays with Fire]

Dip first with a slurry made of good BP meal +5%dextrin, using water/meths (50:50) as the solvent.

You can add some [2-5%] fine pyro metals [Al, Ti, Mgal] to generate lots of hot sparks. Make sure the metals are coated so that they don't react adversly with water! Silica has also been used to good effect here.

Once this has dried off then dip with NC lacquer to make waterproof. Should ignite with a sharp crack every time

Sounds good; I had to look up "meths," but now I know it means Methylated Spirits. Do they sell this at Home Depot (not sure if you have them outside the US, but they're a hardware store chain here)? Where else could I get it?

[Frozentech]

Sounds good; I had to look up "meths," but now I know it means Methylated Spirits. Do they sell this at Home Depot (not sure if you have them outside the US, but they're a hardware store chain here)? Where else could I get it?

Sure they sell it at Home Depot, except in the US it's called denatured alcohol. Just ethanol with a bit of methanol or another poison added to make it undrinkable. Look in the paint & solvents section of Home Depot, it's right between the Naptha and the Xylene

Edited by Frozentech, 23 February 2006 - 08:48 PM.

[Plays with Fire]

Sure they sell it at Home Depot, except in the US it's called denatured alcohol. Just ethanol with a bit of methanol or another poison added to make it undrinkable. Look in the paint & solvents section of Home Depot, it's right between the Naptha and the Xylene

Denatured Alcohol; good to know, the guy at the store told me that is was called Methel Eythel Ketone, or some crap like that...i didn't believe him...good thing

[alany]

MEK is not denaturated Ethanol at all, it is completely different, it is a Ketone, more like Acetone. What do you actually have? MEK, "Metholated Spirits", "Denaturated Alcohol", or "Meths" (which I assume is a brand name?)?

[Frozentech]

Denatured Alcohol; good to know, the guy at the store told me that is was called Methel Eythel Ketone, or some crap like that...i didn't believe him...good thing

Yeah no kidding. The only good use I've ever had for MEK was as a thinner for spraying epoxy-polyamide paints. MEK is fairly nasty to breathe the vapors of, as well. I can't think of a good pyro use for it. You said you were shopping at Home Depot ? They do carry pint and quart cans ( even gallon cans I think ) of Alcohol. It's denatured, which is equivalent to 'meths'. Meths is evidently just a generic British term for alchol denatured with methyl alcohol ( methylated spirits, that is ). I've read that they even use the the term 'meths' the same way we might in the US, call a debilitated alcoholic who drinks wood alcohol, a Sterno drinker !

[Plays with Fire]

MEK is not denaturated Ethanol at all, it is completely different, it is a Ketone, more like Acetone. What do you actually have? MEK, "Metholated Spirits", "Denaturated Alcohol", or "Meths" (which I assume is a brand name?)?

I haven't bought any yet, due to how stupid the store guy was. I'll probably go to Home Depot tomorrow to get Denaturated Alcohol. I'm suprised we don't call it methylated spirits as well, but I guess we have our own way of doing things in our little box with no windows that we call a country...