Nail Polish igniters

[wwattles]

After an exhaustive search through the archives of TRF and other sources, I decided to try the Nail Polish and Graphite technique for making home-dipped igniters.

Started out with plain red nail polish borrowed from my wife, and a little "puff tube" of graphite from the hardware store. I made a little pile of graphite (about the size of a BB) and put 2 drops of nail polish on it and mixed it together and quickly dipped my igniter leads into it. Let stand until dry, and test. Result: No conductivity whatsoever.

So I tried it again, using clear nail polish (bought my own from the store, almost pure Nitrocellulose (a couple alcohols and glycerins thrown in to make it liquid), not even a Camphor stabilizer. Also got a big bottle of graphite from the electronics store. Mixed a pea-sized pile of graphite with 2 drops of the clear polish, which created a semi-runny black paste. Result: No conductivity measured with a multi-meter, and only a couple pinpoint-sized sparkles when subjected to a current.

Question: How much graphite do I need to make this stuff conductive??? And what kind of result should I expect? I'm used to seeing the nichrome bridge wires of Estes igniters give that nice bright flare - should I expect something like that from this, or is it different?

WW

 

[limd21]

How long were the bare ends of the wire leads and how far apart were they?

A good dip, once dry will measure in the 20-40ohm range. I've had ones where the gap was a bit too wide and measured in the 200-250ohm range. Even those work OK if you have enough oomph in your battery. I use a 14.4v nicad pack from my cordless drill - which is capable of some fairly high current. I think these types of igniters require a bit more current than a nichrome bridge version. I've found that that stripping about 4-5mm of insulation, making sure the ends are parallel and no more than 1mm apart makes for the best result. The smaller the gap and the more parallel they are helps the cause. Also, the resistance drops as the dip dries.

If I test one of my igniters with just the conductive dip, I get a fairly healthy bright orange glow. As I always coat with an extra layer of nail polish after the dip is dry, that provides a good bit more of a flare upon ignition - plenty for the black powder motors I use. I don't launch AP motors, so I don't need to mess with metal based pyrogen kickers.

BTW, I use plain, clear, nitrocellulose based nail polish. My mother in law left a bottle of silver metallic polish at our house and I've been meaning to try that as a coating to see if the metal particles enhance the flare at all.

 

[SwingWing]

Be sure it's dry! The resistance is quite a bit higher in a wet or semi-dry state. leave them be for 12-24 hours b-4 testing.

 

[wwattles]

The length I've been stripping/dipping is right around 1/4". I've been spacing them to about one wire diameter, maybe up to 1.5 wire diameters, but only with the phone wire I stripped/twisted myself. (Yes, it's solid core not stranded.)
The gap itself is fairly constant, although that's hard to do. How are you guys going about getting the wires straight and the gap even/spaced properly?
I've also been trying to get the process right with my Igniterman kit, and it's not been going well.

WW

 

[rstaff3]

I am using 30ga twisted wire-wrap wire for my Ignitorman pyrogen. I merely make sure the wire ends are straight, pulling on both wires with a fingernail if needed. I occasionally have to manipulate the last twist to make sure they are parallel. The gap is by eyeball and I've never had a failure. If I cluster with them, I pick the ones with roughly the same resistance, as it will vary some with my non-scientific method.

When I used larger diameter wires, it took more effort to make sure the gap was correct. After measuring the first couple of batches, I moved on to the eyeball method.

 

[Bowhunter]

go to the store and get a pencil refill then take the one and run a continuity test on it then when your happy throw them in a coffee grinder.

 

[gerbs4me]

don't you need Mg in mixture for it to work?

 

[limd21]

Mg or any other sort of metallic powder is not needed. The graphite particles themselves are conductive and when a large enough current is passed through them, they'll heat up very nicely.

 

[scadaman29325]

Maybe your telephone wire has a varnish coating.

 

[rocketkid88]

I imagine adding a splash of BP to the mix would help you get a bit more 'flash', but i've never tried so idn. I hope to try these too soon, but am planing on using some colored nail polish... is that a bad idea?