How to Make a Model Ammonium Dichromate Volcano

Create a Volcanic Eruption...
in the Comfort of Your own Yard

I marvel at what a simple thing it is to just light a pile of a pretty orange-colored chemical, and watch it turn into the what looks for all the world like a volcano.

Just scrootch down on eye-level with the thing at night, and even without the drugs you continue to imbibe, the thing looks real.

Volcano at Night
Not to lapse too technical, but most of the oxidizers we use in fireworks won't even burn, let alone look like a little volcano. So, I marvel at one that does burn and looks so neat.

As you can tell, I am a simple person, amused by the smallest of phenomena.

But I confess, I secretly want to build a giant, 70-foot tall volcano out of ammonium dichromate in the middle of, say, Rodeo Drive, light it, and start yelling "Volcano!"

So, this project is unlike most of our others. There is no complicated mixing of pyrotechnic compositions, nor packing into confined spaces.

Basically, you just pile this stuff up, and light it. But, as usual, Ned Gorski has turned that into something even better.

Take a look as his wonderful little project below and see if you don't agree.

Harry Gilliam

Homemade Volcanoes--For Fun & Profit

A while back I received an email from Harry:

"Have you ever made an ammonium dichromate volcano? They are really popular with parents and teachers and look great daytime or night."

I responded: "Never learned how to make a volcano. Led a deprived childhood. No way they're doin' anything like that in science classes nowadays."

Making a volcano would, of course, be exactly the sort of school project which would capture the imagination of so many young students.

Harry shot back: "Neat little effect. The ammonium dichromate burns by itself, but you can add other fuels to make more lifelike 'lava.' For instance, charcoal 10 or 20-mesh. I imagine there's some flake titanium, ferro-titanium, etc. that would work as well. You could provide volcano formulas for high school projects."

Well, I was intrigued. I've made 16-inch ball shells and 36-inch girandolas, but never an ammonium-dichromate volcano. I couldn't let that stand for long. So I asked Harry to send me a few tubs of the ammonium dichromate, and I put it on my to-do list.

In the meantime, I did a little research on the Internet, and also found a couple of paragraphs about the volcano in the Skylighter Project Plans pages.

Warning: So, first off, a bit of a warning: Ammonium dichromate is rated as a hazardous toxic chemical on its MSDS. One should not inhale its dust, but that's not too tough to avoid since it comes as relatively large orange crystals, not a dust that gets easily airborne.

One should not ingest it. Well, Duh!

One should avoid skin contact. Wear rubber gloves if you're gonna touch the stuff (which is not necessary to create one of these volcanoes). Avoid eye contact. The stuff can cause cancer.

So, exercise appropriate caution with this chemical. If you're going to be making a volcano like this for a science fair, perform all actions and experiments with it outdoors, and when the volcano is "erupting" don't allow anyone to breathe the small amount of smoke and ash, which rises off of it.

Use common sense. I know, I know. Common sense is not in common use nowadays to protect folks from harm. Since everything even remotely dangerous is becoming illegal, folks are increasingly being born with no common sense chip. But, use common sense anyway. There, you see? You got me started.

The scientific stuff: science for kids - old and young

I'm not much of a chemist, but I did find this information interesting, and some other folks might as well.

Ammonium dichromate is sometimes referred to as Vesuvian Fire due to its use in the creation of these small volcano replicas.

Ammonium dichromate's formula is (NH4)2Cr2O7.

Ammonium Dichromate, Skylighter #CH5500
Ammonium Dichromate, Skylighter #CH5500

When it burns, it decomposes according to the following equation:

(NH4)2Cr2O7 (solid) -> Cr2O3 (solid) + N2 (gas) + 4H2O (gas)

The gaseous byproducts are simple nitrogen gas and steam, so they are innocuous.

Chromium Oxide Ash Left After Ammonium Dichromate Volcano Burns
Chromium Oxide Ash Left After Ammonium Dichromate Volcano Burns

The solid product is chromium (III) oxide. What remains after the volcano burns is this solid, grayish-green ash. The chromium in it is toxic and possibly carcinogenic, so care should be exercised when handling it and disposing of it. Some of this ash flies up into the air when the volcano is burning, so you don't want anyone close enough to it to breathe the stuff.

The chromium oxide can reportedly be used in a thermite reaction to produce elemental chromium metal, so I'm going to save the chromium oxide ash to try to use it in such a reaction, since I am planning an article on thermite reactions.

A volcano project

I decided to go simple, and make a "volcano" out of a can and heavy-duty aluminum foil. I formed a lip at the bottom of the aluminum foil "cone" to catch the ash as it formed.

Making an Aluminum Foil/Pop-Can Volcano
Making an Aluminum Foil/Pop-Can Volcano

I lit the top of the ammonium dichromate with a propane torch, and it burned and created a "volcano" effect, but at times the flame went deep into the orange crystals, down the sides of the can, and propelled some of the crystals up and out of the can, unburnt. I was not completely pleased with the effect that was produced.

So I decided to try a shallow, tuna-fish can, sitting on top of the pop can.

Aluminum Foil Volcano Made With a Shallow Tuna Can
Aluminum Foil Volcano Made With a Shallow Tuna Can

This volcano burned a little better than the first one, but still the flame worked its way down the sides of the can, and the ammonium dichromate did not burn evenly. I still was not satisfied.

I also noticed that igniting the ammonium dichromate with the propane torch was not all that easy. The pressure of the propane blew the crystals out of the way of the flame, and although some of them eventually lit and initiated the desired continuing reaction, the pile did not ignite right at the top of the heap.

So, I decided to try something really simple. I made a "tray" out of flat aluminum foil with the edges turned up to catch the ash. I poured a cone of about a half-pound of the ammonium dichromate in the middle of the foil tray, and inserted a 6-inch length of Visco-fuse into the middle of the pile of orange crystals.

Simple Pile of Ammonium Dichromate to Create a Model Volcano
Simple Pile of Ammonium Dichromate to Create a Model Volcano

Once the Visco fuse burnt down into the cone of crystals, they ignited and a nice volcano-action formed and burned until only ash remained.

Well, then I thought that the way to get this baby really looking like a volcano, but still burn like it did in this last test, was to form the aluminum foil over the cans, but not cut the opening. I just piled the ammonium dichromate on top of this "mountain" on the flat section and inserted another piece of Visco.

I was really pleased with how this volcano looked and performed.

Daytime Ammonium Dichromate Volcano
I think it almost looks like the real thing with glowing, flaming lava flowing down the side of the Mt. St. Gorski.

Making model volcanoes this way uses about 1/4 pound of the crystals per volcano.

Nighttime volcanoes

I thought I'd make a few other versions of the ammonium dichromate volcano at night.

For the first one, I repeated the procedure I followed in the last daytime test. This looked pretty cool as the "lava" burned and flowed down the sides of the "mountain."

Honestly, I like watching the volcano better in the daytime when I can see the greenish ash being formed and flowing down the sides of the hill.

For the second nighttime volcano, I did the same as above except I stirred in a tablespoon of 36-mesh charcoal to see what sort of effect that would produce.

As this volcano burned, a lot of orange, charcoal sparks rose up into the air above it, creating an effect that was different than the standard, ammonium dichromate-only volcano.

For the third nighttime test, I mixed in about a tablespoonful of medium flake aluminum, and for the fourth and final test I added about a teaspoon of fine spherical titanium.

The addition of these metal fuels seemed to slow down the burning reaction, and did not produce the silver-white sparks, that I was half-expecting. There was an interesting, different sort-of molten flowing effect, as the reaction seemed to almost melt the ammonium dichromate and metal together, causing molten "lava" to flow down the mountain.

As a last offering to the pyro-gods, I simply poured about a half-pound of the ammonium dichromate onto a bare patch of ground and lit it with the propane torch.

Simple Ammonium Dichromate Volcano On the Ground
Simple Ammonium Dichromate Volcano On the Ground

This caused the little volcano crystals to ignite from the sides and burn toward the center, and this was probably my favorite effect of the night. (After it, I had to get a shovel and completely clean up the green ash from the area.)

Simple Volcano


This was a fun little science project. I saved some of the ammonium dichromate for when my grandkids visit, and I'll introduce them to something they'll probably never have the chance to see in science class. And there's enough left to show them how to make a school project volcano just in case that time comes.

I learned something today working on this model volcano, and that's never a bad thing.

Take care and have fun,

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