I'm having a bit of trouble with my thermite. I read an article that suggested adding equal parts Mg and Al (Visually equal) and Iron oxide and mix together. The article said that thsi would make the thermite "Match light". And it did, to an extent. It would ignite, but only the top "Layer" Of my thermite mound.
When it was done huffing and puffing, there would be a top layer that was burnt out, but everything underneath was still untouched.

Is there a problem with my mixture, or maybe my technique? I'm using rust scraped off the top of a BBQ. I filed down Mg from those fire starter kits, and the Al came from a bar I had from god knows where. I crushed the rust down in a glass container (Don't have a morter and pestel anymore). It looks pretty fine, but there are still some larger chunks.

first off, I hope you wore a mask or took the necessary ventilation steps to make sure you didn't inhale any of those nasty rust particles.

and second, I think you should read up on particle size and how it affects chemical reactions

and lastly, it might be in your interest to check out activation energy...reason being you may need a high temp composition to start your thermite reaction.


like KMnO4 and glycerol.

try adding a bit of sulfur to your mix.

you get the same reaction if you light normal thermite with a match. The flaring of the match head is hot enough to light the thermite immediately around it but not enough to get the reaction going to the point where the heat generated will light more thermite. One way I like to use to light thermite is to use a tissue to contain a ball of sucrose and potassium perchlorate with a fuse sticking out of the top. This mixture will burn hot enough to light the thermite (making the magnesium unnecessary).

Thanks for the replies, I got some pretty good ideas. Spongebob, do you think your method for igniting thermite would work with magnesium? I don't really have access to the items you suggested.

Try adding some sulfur to your mix just a little but of course that depends on how much your making. Sulfur will raise the ignition temperature of many compositions although watch out in future with mixing it with chlorate's if you ever do.

For ignition I use kno3-Al flash again with a little sulfur to lower the ignition temperature.

Ratio: 3:2:1 (kno3:Al:S)

kno3 flash burns really slow and hot and can be ignited using a bit of visco fuse or black match thus providing in my opinion the optimum ignition mix.

If by magnesium you mean magnesium powder being lit by a fuse then, no safety fuse does not burn hot enough to light magnesium.

Magnesium ribbon can and does light thermite but I tend to not use it because it can fall over in the mixture after it is lit and go off in your face.

Sorry tordek but I have to say that using flash seems like a bad idea because the last thing you want is burning thermite being thrown up into the air.

The perchlorate/sucrose mixture is safer (in my opinion) because it does not explode and it is more forgiving with ratios.

Iv found that using reasonably high mesh AL and kno3 tends to produce more of a slow, hot burning composition rather than a composition that would throw thermite in the air.

Plus with the fact that you can use fuse to ignite it you don't have the problem of it flying up in your face.

A rather noobish question - but is there a way to tell the size of particles that didn't come prepackaged? (if that made any sense. If not, here's an example My rust that I got off my BBQ and crushed. Is there a way to find out the size of the particles?

usually you use screens, which are like sheets of woven metal. I doubt you'll have that really hanging round, so you could liken it to household items - flour/salt.

There's also a calculation to work out the mesh size of your particles, but i doubt they're standardized, or that you have a method of measuring it. Somewhere a bit finer than salt and you're fine I'd say, for a reasonable thermite. A finer mesh would be nicer for the top layer.

Thanks for that Vos - I feel a little embarrassed for asking that, now that I think about the question.

So my thermite mixture is fine? A visual 1:1 mix of rust and Al? I've seen so many variations, that I'm not sure what to take as fact.