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Harmless
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Thermite Igniter?
I have been trying to get thermite made to study its controllable varriables (for welding and cutting, as seen in my post in the gen chem area) I probably should have posted it here in the 1st place, but I am now.
I made some this weekend and attempted to ignite it with a form of KMnO4 + Glycerin. (when that didnt work I used an oxy/acetylene torch, but it
blew/scattered the mixture before it would ignite)
As for the Potassium Permanganate and Glycerin...
What is the propper mixture? actualy better yet, I had assumed that Glycerin(e) was the same base product as glycerol. One chem book shows them as the
same thing, but different forumula's, and another shows them as the same thing alltogether. A little googling gets the same contradicting
response.
So which is it? or rather which is which? and which is required to ignite thermite?
Or if there is a different ignighter that is known (besides Mg ribbons) that would work.
If the potassium permanganate is the better way to go, aprox how long does it take for the reaction to peak? When I mixed my "clear water"
purple fishtank crap that listed KMnO4 as its main ingredient, and a few drops of the glycerin, they just stayed seperated. about 5 min later the
purple turned red. thats about it. Is there a way to test to see if its even going to work? (I put it on something combustable at low temps like a
paper towel)
What is the temp required to ignite thermite anyway? I have read different things, 300 C, 600 C, 1200 C, etc.
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The_Davster
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Glycerin and glycerol are the same thing, it can be bought at the pharmacy. From your posts in the othe thermite thread I got the impression that
your permangante is a solution? It must be a powder mixed with the glycerin that will ignite to catch the thermite.
[Edited on 11-4-2004 by rogue chemist]
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BromicAcid
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When I used to make thermite I mostly worked with cast thermite. Basically this is thermite that has been mixed with some plaster of Paris and water
and allowed to harden. I made this in an ice cube tray. Being that they were in block form they held together easily enough to be ignited with a
butane torch. I know that these would lead to unacceptable impurities in any welding application but, you could take a piece of wire and put it into
each block. When you wanted to ignite your powder thermite you could take a block of it on a string and hold it above the larger thermite charge till
it caught, then lower it into it to catch the rest. Thermite reactions are usually none to violent and being that they propagate fairly slowly you
should have plenty of time to lower the smaller charge into the main mass and get away before things really start to get hot to the point of danger,
as always, experiment on a smaller scale first.
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Son of Northern Darkness
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I'm not sure what temp it is to ignite thermite but it isn't really that hard. Some mixtures that work
KClO3/Sugar
KMnO4/Sugar
KMnO4/Glycerin
Usually a 50/50 mix by volume is good enough.
Sparklers also work.
EDIT: Bromic, holding a lump of thermite by some string and lowering it down, while lit, into more thermite? That's one thing I dont really wanna
try.
[Edited on 22-4-2004 by Son of Northern Darkness]
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hodges
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A mixture of approximately equal mass of Al powder and powdered sulfur is easy enough to light with a torch and plenty hot enough to ignite iron
thermite. When I was doing my thermite tests I ignited the Al/S mixture using a piece of string soaked in KNO3 solution and allowd to dry. The burn
rate was unpredictable, but it always eventually ignited the Al/S.
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BromicAcid
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| Quote: |
Bromic, holding a lump of thermite by some string and lowering it down, while lit, into more thermite? That's one thing I dont really wanna try.
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Well I guess you could put it on the end of a fishing pole if it really scared you that much 
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Saerynide
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Wont the fishing pole melt/catch fire?
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t_Pyro
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Not if you're using a titanium wire with your fishing pole...
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Hermes_Trismegistus
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This is a dead thread.
It was crossposted with his other thread.
We found magnesium ribbon cheap and readily availible off ebay, and chemoleo has provided that sparklers will do the trick if you stick one right in
the middle of a pile.
Arguing on the internet is like running in the special olympics; even if you win: you\'re still retarded.
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Lestat
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I have never been able to get Mg apart from when I was in school, so I improvise and use lithium from a battery which burns rather well...
The meek arn\'t going to inherit everything, their greedy relatives will get there long before someone bothered to tell the meek than someone has
died.
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Saerynide
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Electric Ignition?
The tungsten filament in a lightbulb is supposed to reach 2750K. Could a small broken light bulb (those 4.3v ~1cm in diameter ones) with the filament
intact ignite thermite when stuck into the mixture? If this works, this would be an awesome electronic igniter
[edit]; Typo
[Edited on 20-1-2005 by Saerynide]
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The_Davster
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I am not sure that would work Saerynide. When electricty is run through the bulb when the glass has been broken off, the filament burns away very
quickly. The lightbulb igniter does work with more sensitive powders(like gunpowder) but with thermite, the filament may reach 2750K, but only for a
few fractions of a second, so not enough energy would be transfered to the thermite in order for it to catch.
[Edited on 20-1-2005 by rogue chemist]
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Quince
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Use an arc. Sufficient voltage is needed for dielectric breakdown of air (~3 kV/mm), but you need high current to get high temperature. A flash
mechanism from a disposable camera can be adapted for this, as it generates a very high voltage pulse to ionize the bulb, and then discharges a
capacitor that's only a couple of hundred volts.
A simpler way, however, is the following. Two carbon electrodes (such as those taken from alkaline batteries) are fixed with a few mm gap between
them. Bridge the gap with the filament from a small fuse, making sure it makes good contact with both electrodes. Send a large current through the
electrodes. The filament will vaporize and an arc will form between the electrodes, turning the tip of the anode at least white hot and causing it to
start vaporizing. The power source could be as simple as directly from the outlet ballasted with a 500+ W halogen light or heater (even better if it
has a switch), but I recommend using an isolation transformer (1:1) of sufficient rating (if you don't have one, just use two microwave oven
transformers back to back, with their high voltage secondaries connected together -- note that this configuration will cause the transformers to heat
a lot, so it should not be run more than a couple of seconds). Discharging a capacitor will not work here, as the pulse doesn't last long
enough. If you don't want to have to reload the filament every time, you could make one of the electrodes movable and adjust it with pliers with
insulated handles; briefly touch it to the other electrode to start the flow, then pull away a few mm to get a good arc. DO NOT STARE AT THE ARC
--> UV WILL DAMAGE YOUR EYES! Use UV blocking sunglasses. Also, make sure to do it outside or in a well ventilated area. The temperature does
break down some of the O3 and NOx generated, but it still stinks and breathing it will hurt you.
The description is long, but I've used this (although not to burn things, just to melt some metals in a ceramic pot, with a 1.5 kW heater in
series as ballast). I have no doubt this will very easily ignite thermite (best to heat the thermite from below; do not stick the electrodes in the
mixture as it will conduct).
Disclaimer: If you are a newbie and don't know how to handle high voltages, I wouldn't recommend this method. If you damage or kill
yourself, you have no one but yourself to blame.
[Edited on 4-2-2005 by Quince]
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uber luminal
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| Quote: | I have no doubt this will very easily ignite thermite (best to heat the thermite from below; do not stick the electrodes in the mixture as it will
conduct).
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Sorry to doubt you, but have you ever put an arc near powder?
not only would an arc not be practical for redox, (cuz if you have the arc, who cares about some dumb redox), but putting any arc near powder sends
the powder in every direction but where the arc is. I run into this problem at least twice a week when trying to arc melt germanium or silicon
powders/small bits. So I say, crap! and think oh yea, ill just put the arc near the powder and hope the radiated heat melts it, or at least melts it
together a little, but nooo. If the arc isnt close enough to the powder where its blowing it everywhere, its not hot enough to melt it. (granted we
arnt trying to melt the redox components, just ignite them, I still stand by the fact that it will blow the powders everywhere, unless maybe you have
600 amps handy, then the heat might be sufficient, but that goes back to the why bother stage.
btw, the way I get around the arc-powder problem at work is to put the powdered stuff under a large piece of metal to be alloyed. If its all powder,
we have cranked the amps up into the 600-800 range and used a circular motion around the sample alloy. this ussualy gets it to stick.
and I have gotten KMnO4 and glycerin to work. Iv found it easiest to pour a little glycerin onto an edge of the redox components, and then use a
scoopula to put some KMnO4 into the glycerin puddle. That works better than putting glyercerin into a divit of KMnO4 powder (and less wasteful of the
oxidizer!)
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Saerynide
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| Quote: | Originally posted by uber luminal
and I have gotten KMnO4 and glycerin to work. Iv found it easiest to pour a little glycerin onto an edge of the redox components, and then use a
scoopula to put some KMnO4 into the glycerin puddle. That works better than putting glyercerin into a divit of KMnO4 powder (and less wasteful of the
oxidizer!) |
Ooooohhh... thanks I tried adding glycerin to KMnO4, but that never worked.
This time, if sparklers dont work, I'll try this
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Quince
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| Quote: | | Sorry to doubt you, but have you ever put an arc near powder? |
No, but close: I have put a 5 cm, 1+ kW DC glow discharge (MHCD sustained) to powder (sugar -- quickly turned to ash and gas). Modified microwave
oven transformer->rectifiers (chained common ones)->CLCRC filter (total 160 uF / 3 kV capacitance, the L is handwound around salvaged tranny
core). I'm replicating Hill's Plasmatronics, except without helium, as MHCD techniques now allow large glow discharges in air without
cathode fall instabilities and discharge-to-arc transitions. It's true that the glow discharge moves less air than an arc (AC at that), but I
doubt that the arc would blow heavy metallic-based powder around (especially if binded with plaster as suggested by someone).
[Edited on 5-2-2005 by Quince]
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Mr. Wizard
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Use 6" of 1/16" flexible steel cable hooked to a set of car jumper cables. It gets white hot incandescent within seconds and will light even
course thermite.
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Theoretic
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You could take some anhydrous CuCl2 and wrap it in Al foil, this can be ignited with a candle and gives a very bright and (presumably) hot white flame
which I'm sure will ignite thermite.
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chloric1
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Really?
Never tried this. Maybe you could put some aluminum shreds in with the cupric chloride? Hmmm, like to see this work.
Fellow molecular manipulator
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Saerynide
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The light bulb did not work  I tried a drop of glycerin then sprinkling on KMnO4,
but nope, that didn't work either. I think I added a bit too little KMnO4 (I usually use too much and end up wasting it, so I was trying to be
more conservative time time  ).
I wonder, would it work if I put a few drops of glyercin in a divet of thermite, then scoop on a spoon of KMnO4? Or would all the glycerin get soaked
into the thermite and nothing would happen?
Btw, do you usually powder your KMnO4? (if you do, maybe thats why mine doesn't ever work  )
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I am a fish
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How long did you leave the Potassium Permanganate / Glycerol mixture before disposing of it? There is usually a significant delay between the two
being mixed, and the mixture igniting.
1f `/0u (4|\\| |234d 7|-|15, `/0u |234||`/ |\\|33d 70 937 0u7 /\\/\\0|23.
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Saerynide
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A long time. Ive seen it take a long time before, but this one, it just sat there, and did nothing, not even after a few minutes
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The_Davster
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What temperature was it when you tried this? At times I have been unable to have sucess with permanganate/glycerin when it is too cold outside.
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uber luminal
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| Quote: | | but I doubt that the arc would blow heavy metallic-based powder around (especially if binded with plaster as suggested by someone).
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it really does blow it around. it doesnt matter what the density is. I have blown tungsten bits around. If you can blow tungsten, im pretty sure it
wont matter what the material is. I deal with this on a weekly basis, its a pain in the ass.
Saerynide,
I think the glycerin would move too quickly and contaminate your mix if you dropped it right into the redox components. My KMnO4 is a dry purple
powder itself. I bought it on ebay for $10 /lb.
You can use KMnO4 as a liquid, and it will react with the sugars (as they dissolve into the aq soln), but it will not get hot enough to do anything
with it, you probably wont even see anything happen because the concentration of the KMnO4 is soooo looow.
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Saerynide
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My KMnO4 are little crystals. I guess I should grind it up into powder.
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