Friction igniters?

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Fulmen
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Friction igniters?

Post by Fulmen »

Have any of you guys made pull-string type igniters? Shouldn't be too hard to make, but can it be done without red P or sesquisulfide?
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Fulmen
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Re: Friction igniters?

Post by Fulmen »

Someone suggested that chlorate/realgar might be sensitive enough. Perhaps a realgar-coated wire and a more conventional chlorate mix could work?
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Lloyd
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Re: Friction igniters?

Post by Lloyd »

Most 'pull' igniters also contain an abrasive, like crushed glass or fine sand. I've read about them, but never made them.

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Fulmen
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Re: Friction igniters?

Post by Fulmen »

I didn't mention glass as I considered it obvious:-)

I have made "match heads" for safety fuse in the past from spent 22LR cases. They were perfect for the job, being a tight slip fit on plastic coated "blasting fuse". IIRC the comp was KClO3/S/MnO2/ZnO/glass/PVA, but it did of course require a matchbook strike surface.
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Re: Friction igniters?

Post by Lloyd »

"I didn't mention glass as I considered it obvious:-) "
------------------

It wouldn't be obvious to someone unfamiliar with the technology/formulae!

Even if you think you're being redundant or pedantic, never leave out essential ingredients from a formula.

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Fulmen
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Re: Friction igniters?

Post by Fulmen »

I know, I know. I'll make sure to be more specific if I decide to go down this rabbit hole. Right now it's just a "feasibility study", I'm even considering synthesizing red P from scratch.

So what are the best/worst sensitive mixtures available?
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Pyro-Gear
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Re: Friction igniters?

Post by Pyro-Gear »

Potassium chlorate 45
Antimony Trisulfide 10
Glue (animal source) 25
Airfloat charcoal 10
Ground glass 10

Another
Potassium chlorate 50
Antimony Trisulfide 20
Glue (animal source) 20
Sulfur 10

You can not use red gum or shellac to substitute the animal glue!
Animal glue is basic, which adds to the safety, while both red gum and shellac tend to be slightly acidic
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Re: Friction igniters?

Post by dave321 »

ken,
do the above need a match striker ?
or are they sufficiently sensitive to ignite with a roughened wire pulled through a small pellet ?

isn't animal glue made of gelatin (hide glue ?)
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Fulmen
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Re: Friction igniters?

Post by Fulmen »

@Ken: Those two look like typical match head comps. I haven't considered the pH of the glue before, that's worth noting. On the other hand I'm pretty sure I've seen comps using PVA, and as far as I know that's slightly acidic. Then again most comps (especially those containing sulfur) include a base, zinc oxide is pretty common.

The match comp I used in the past was this:
KClO3 - 50
PVA-glue - 15
Ground glass, 120# - 15
Sulfur - 5
MnO2 - 10
ZnO - 5

Didn't have any issues with it, but I never torture tested it.
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Pyro-Gear
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Re: Friction igniters?

Post by Pyro-Gear »

dave321 wrote: Sat Oct 26, 2019 4:58 pm ken,
do the above need a match striker?
or are they sufficiently sensitive to ignite with a roughened wire pulled through a small pellet?

isn't animal glue made of gelatin (hide glue ?)
Scratching against a matchbox or rough surface will ignite the mixture. To prepare this composition, mix the potassium chlorate with the glue and carefully knead in the antimony trisulfide, hide glue is what you’re looking for.

@ Fullman, I have known people to use Elmer’s and I believe that is a PVA.
But https://www.ebay.co.uk/itm/Titebond-Liq ... SwbgJanxAT

Note these compositions are very sensitive too nearly anything,
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Re: Friction igniters?

Post by dave321 »

also, a simple mix of chlorate with resorcinol resin, to a thick gloopy consistency,
will set hard and be strikable using a safety match box striker
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Re: Friction igniters?

Post by Pyro-Gear »

I would need convincing on that one Dave?
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Re: Friction igniters?

Post by dave321 »

i tried it years ago pasted onto the end of chinese time fuse,
it set hard and was easily ignited with the safety match side strip.

the resorcinol resin was if i remenber correctly 5parts resin to 1 part hardener

"cooperman" phil cooper used to sell the resin, might have been the same as "west systems"
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Re: Friction igniters?

Post by Pyro-Gear »

I played with resorcinol resin way back for a crackle composition and a few comets, however if you’re saying it works as a strike ignition I will give it a go, there is nothing special about resorcinol that in my opinion would give any advantage over a catalyzed NC but I am up for a test on your findings, shame the post is falling on deaf ears to some members but I will try it.
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Re: Friction igniters?

Post by Pyro »

dave321 wrote: Sun Oct 27, 2019 5:13 pm also, a simple mix of chlorate with resorcinol resin, to a thick gloopy consistency,
will set hard and be strikable using a safety match box striker
We used that on a certain prototype product. You should add some catalyst and probably something to increase the friction though to make it sensitive and reliable enough.

I think any binder that dries or cures hard and brittle can work. Phenolic resins are not unique as fuels in this application.
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richardh08
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Re: Friction igniters?

Post by richardh08 »

As Ken mentioned, he and I played with resorcinol-bound crackle a while back. At the time, we found that there were some doubts about its safety. Way back in 1989, Lloyd Scott Oglesby published an article, reporting that several people using it had experienced unexpected ignitions and explosions. He recommended that it should not be used together with ammonium perchlorate, potassium chlorate, barium chlorate, copper oxide or magnesium.

We didn't look into the problem in any detail, but never found any sensitivity issues with our CuO-based crackle compositions. LSO appeared to associate the sensitivity with the acid nature of the resorcinol resin they were using, but the resin I had (from Cooperman) was alkaline, rather than acidic.

Potassium chlorate definitely generates unstable compounds in an acid environment. I'm not saying the use of resorcinol with KClO3 is is necessarily dangerous, but this potential issue is definitely something that is worth keeping in mind.
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Fulmen
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Re: Friction igniters?

Post by Fulmen »

I suspect that almost any chlorate compound could be ignited with a strike pad. IIRC the reaction is caused by white phosphorous produced by friction heating of red P. Now white P is pyrophoric in its own right and seems to react instantly with chlorates. That's the beauty of the system, basically it's a hypergolic mix.
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