What binder for thermite?

Apr 5, 2004
I made up a small batch of thermite a while back, and rather than keep as loose powder, I'd like to compress it into pellets for ease-of-use issues, and also to insure that the aluminum doesn't seperate out. What sort of binder should I use? :confused: I'd want to make sure it wouldn't inhibit the reaction, of course.
I can't answer your question but I am curious about what you will use thermite for.
I'm going to recommend gum arabic, but that a bit speculative. Chemistry is not my field of study but I believe if you use much binder at all it is going to inhibit the reaction significantlly. (Think, why does thermite use powdered metal?)

I suggest googling for pyrotechnic binders.

This might interest you:
wikipedia said:
Thermate-TH3 is a mixture of thermite and pyrotechnic additives which have been found to be superior to standard thermite for incendiary purposes. Its composition by weight is generally thermite 68.7%, barium nitrate 29.0%, sulphur 2.0% and binder 0.3%. Addition of barium nitrate to thermite increases its thermal effect, creates flame in burning and significantly reduces the ignition temperature.
Mostly geekish persuits of science. Field expiedient proof of concept type stuff. Light welding and fabrication. (Why? To see if I can, of course.)

After all that, I have a small interest in burning a very large hole in a very annoying steel door. (I own the door, of course. I've spent a good deal of time thinking of the best way to make it suffer for it's crimes. The splitting maul will likely see action here, as well.)
You should not need a binder for thermite. Most binders will require a solvent and I have never heard of using a solvent with thermite.

All you need to do is compress it. I would suggest some kind of paper tube and then get a wood dowel or metal rod that fits inside. Add increments of the thermite mix and smack with a hammer.

Thermite is very hard to lite. The end you are going to light you probably want to mix 80% thermite/20% black powder. Then a layer of 60% thermite/40% black powder, so on until you have just black powder. A fuse should light this. Otherwise, a piece of magnesium ribbon should get the job done.

We need pics of the offending metal door and its final condition! :D:D
Yea, what were you planning on using for starting this off?

edit: if you're looking for Mg, I think that ERdept was selling some shavings...
I have messed around with alot of thermite for producing iron and making some alloys for knives. As cantankerous as it is to light a binder will very likely prevent the reaction. But with some experiementation I will be that one could be found.

I have made some all weather fire starters with it by packing it in some 3/8" pyro tubing. The fuse is regular cannon fuse that lights mag ribbon which then lights the thermite.

Even if you never find a binder for it it will still be loads of fun to play with.
Method of ignition will likely be magnesium ribbon. I'd like to try some of the more esoteric methods, but I'm too lazy to hunt down the chemicals.

I've tried just striaght compression without a binder, but I must not be going about it right. Half burns, and the other half just gets blown apart. (powdered rust stains stuff real good, as it turns out. . .)

I tried compressing into a casing. Aluminum burns/melts too quickly,steel and brass gobble up too much heat. (Maybe clay or ceramic?)
For cutting a big hole some shaped charge stuff would be more appropriate.That's what they use to take down buildings.
I tried compressing into a casing. Aluminum burns/melts too quickly,steel and brass gobble up too much heat. (Maybe clay or ceramic?)

Metal casings cause more trouble than they're worth. Commercially available thermite typically uses a ceramic casing.... or "pot"

One thing that works well is a small (1 pint or so) terra cotta pot and saucer that are available at your local lawn and garden store. The pot can be used with a drain hole in the bottom and covered with the saucer to provide a "drip" for cutting steel. Without the hole, it acts as a crucible for melting metals. I've even seen the pots broken and chipped to make forms, for welding odd shapes. Refractory cement comes in handy when doing this.

there is alot of info bout thermite and diy steelmaking on swordforums, checkitout, they know the best ratios i´d guess
A proper thermite mixture will quickly produce temps in excess of 6000 deg F. Very few materials can contain that amount of heat for any length of time. Silicon Carbide and magnesium oxide are a couple. The other option is using sacrificial mass. A good mixture is 50% wood ash and 50% powdered charcoal mixed to a thick mud consistancy and layered inside a earthen container. After it dries it will hold up just long enough to contain 3 Lbs thermite charge.

I found sparklers to be the best ignitors since they are not dependant on O2 to burn.

This is the last charge I did using the 50/50 mixture of ash and charcoal. The charge has a lid on the crucible and the low O2 would not allow magnesium ribbon to burn. I used a bundle of four sparklers and it took off within seconds.


Good luck and have fun experimenting!
How about some very thinned epoxy, enough to hold it together without the bulk to affect the reaction?
that shouldn't work
you're relying on the close contact of the powdered particles for the reaction to take place
anything that doesn't burn will inhibit it for sure
I used to use powdered magnesium mixed with sodium nitrate as the ignitor. Try compressing the thermite mixture in a vice with a die, don't get it wet though.
i don't think it will inhibit the reaction, but it will certainly make it harder to light. Anyonesee the hindenburg episode of mythbusters? They actually made a thermite dope (metrallic paint coating) for the skin of their scale airship and it did react, in fact, even the seperate aluminum and iron dope layers had a minor reaction.