Introduction: Fun With Bismuth

Picture of Fun With Bismuth

Bismuth is a lesser-known metal. It isn't seen in consumer products much (it has some applications in manufacturing) and isn't particularly rare or valuable. A good overview of bismuth is here.

It has several qualities that make it suitable for amateur experimenters: it's not poisonous, it has a fairly low melting point, it's cheap, and it has a really lovely crystalline structure. It's great fun to play with.

I got the health question a lot from people I mentioned this project to. Unlike lead, mercury, nickel, or other metals, there is no significant health risk from vapors or from touching bismuth or ingesting small amounts (it's actually the active ingredient in a popular brand of stomach medicine). There is of course a burn risk when you melt it, but adequate precautions and basic care reduce this to levels that are quite acceptable for me - it's really no riskier than boiling a large pot of water.

Step 1: Equipment and Safety

Picture of Equipment and Safety
Bismuth's melting point is 520 F, 271 C. This can easily be achieved on a stovetop or, as I did, with a camping stove. It will coat the interior of your crucible so don't use something you cook with often.

As with nearly anything these days, bismuth can be purchased on the Internet. I got a pound for about $15 US. This turned out to be a cube (more or less) of an inch and a half to two inches on each side.

Obtain the following additional items:

  • goggles in case of splashing
  • leather gloves
  • crucible - stainless steel pot or bowl
  • heat source - stovetop works fine, i used a camping stove
  • big tweezers to pick out crystals
  • pliers to handle crucible if it has no handle

The crucible I used (OK it's a mixing bowl from IKEA) is a little big for the pound of bismuth I got. Because melted bismuth oxidizes so fast, you want as small an area as possible exposed to the air. Also it would have been slightly easier to handle on my camp stove.

I got my bismuth from Rotometals for $15 plus about $7.50 shipping, which was lowest for my location. Other online sources sell it as well.

Step 2: Melting

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This is very straightforward. Turn on the heat and wait. Full melt took about 12 or 15 minutes at whatever temperature I was getting from the camp stove.

Step 3: Crystals

Picture of Crystals

Once the bismuth is all melted, turn off the heat and let it cool down. As the metal cools, it will create crystals under the surface. Poke it gently with the tweezers and you'll see where solid pieces have started to form. Gently pick these up and turn them over to see the crystalline structure underneath. Not all pieces will form the beautiful step-wise cubic crystals, but you can remelt any that you don't want to keep.

The iridescent colors are caused by oxidation, which happens very quickly when the melted bismuth is exposed to air. It may be possible to reduce this by plunging the crystal immediately into water, but I did not think to try this - next time!

Step 4: Pouring Into Water

Picture of Pouring Into Water
What would melted bismuth do when water cooled? There is only one way to find out! We set up a little screen for me just in case there was a lot of splashback, but this turned out to be unnecessary. Here's a video:

The picture shows the results. Notice there is no oxidation!

Step 5: Pouring Into Molds

Picture of Pouring Into Molds
Here at Instructables HQ we have lots of weird stuff lying around. We found an old silicone mold from last Valentine's Day and poured the melted bismuth into it. The results were not astoundingly great visually, but the process was excellent and the cast bismuth hearts are satisfyingly heavy in the hand. With some experimentation a better cast could surely be produced.

We also poured some and attempted to insert pins to make pushpins. This did not work so well - the plastic one melted and the nail is loose. It was moved slightly before the bismuth was quite solidified -- and the bismuth doesn't stick to steel.

Step 6: What Else?

Picture of What Else?

I remelted the pieces five or six times. After a while there was a crust on the top of the melted metal that didn't seem to want to flow back under. It's not crystalline and it wouldn't melt. I suspect this was just some that got particularly heavily oxidized after all the melting and solidifying.

I sanded the back of one of the crystals that was particularly beautiful. I will epoxy a loop onto it so it can be worn as a pendant. What with the non-stickiness of the bismuth I'm not sure epoxy will bond to it but I'll update this when I find out.

One thing I noticed was that the bismuth did not bond to things very strongly. It got all over the ends of the tweezers but I was able to crack most of it off once it had cooled down. It splattered a bit over our metal table but didn't stick to that either. It didn't stick to the silicone mold at all (of course this is also a property of silicone). It didn't stick to the nail. I was able to crack some of it out of the mixing bowl, although not all. The bismuth particles on the sandpaper fell right off too, unlike most things which tend to stick to the grit, and can only sometimes be brushed or tapped off.


Jimmy-leeS (author)2016-09-29

What will happen when mixed with gallium?

wenw (author)2016-04-28

do u think that soap stone can be used as the mould?

JoshA11 (author)2015-05-30

This project was pretty cool. I made my bismuth crystals from bismuth bought here:

carlo.dangelo (author)2015-04-06

Just because bismuth subsalicylate is in Pepto-Bismol does not mean Pepto-Bismol is toxic. Think of oxygen.. It's two oxygen atoms joined together by a double bond. It's safe as we all know. Add another oxygen to the mix and you O3 which is a poisonous gas called ozone which is a deadly oxidizer and will eat away at the mucous membranes of your lungs.

Did you think something as minuscule as an extra oxygen atom to O2 could be so deadly? The same applies to medications. If you only knew what chemicals are used in the manufacture of many of the drugs we all consume on a daily basis..

The point I making is that while this is a heavy metal, the anti-acid Pepto Bismol is safe to consume.

I have to wonder, if someone went about bismuth crystal production from a chemist's perspective could you possibly use a stir bar on top of a hot plate in a aluminum pot at the moment where the temperature is ripe for crystal formation to yield a winding staircase effect?

WesChandler (author)2014-08-23

I would advise against putting molten bismuth in water. I've done it. It exploded and I ended up with bits of molten bismuth all over me (thankfully not on my face). Needless to say, it was extremely painful. I later realized this happened because, like water, bismuth expands when it solidifies. When I put molten bismuth in water, the outside solidified before the inside and a moment later it went everywhere.
But, this is a really good idea for making crystalline. I'm definitely going to try it. Thanks!

techchimp (author)2014-06-17

First off, love the topic and good instructable!

Second, a word or two about safety...

Bismuth metal is "safe" to use if you can guarantee its source. If you are unsure of the composition, you should take vapour and handling precautions (gloves and masks).

Some alloys of bismuth contain cadmium, lead or other toxic compounds.

You can always spray a clear-coat on your finished crystal if you are concerned about handling the metal.

craftyv (author)2014-01-30

The melted Bismuth needs pouring into another warmed pot holding back the grey "slag" so it doesn't go with the Bismuth. Then let the Bismuth cool as slowly as possible because this is how the crystals are formed. This will give much better results. Good luck.

emcelhannon (author)2013-11-05

Where do you buy it for $15 per pound?

Many thanks,

draghi (author)2010-03-20

The link you posted is good... except to get shipped to Australia it costs $92.23 for one pound of the stuff.

cathyjblake (author)draghi2012-04-22

You need to have someone ship it to you in a USPS International Flat Rate box, it's only $17 for a small box to Australia.

coolo52 (author)2012-02-29

i love how you said that the melting bismuth reminded you of the wicked witch of the west.

javajunkie1976 (author)2011-06-14

Looking at the first photo, it's kind of amazing that nature would create something like that. Beautiful and mesmerizing are the terms that come to mind...

coolo52 (author)javajunkie19762012-02-29

you are so right it is very beautiful and mesmerizing

8v92 (author)2011-12-10

What makes an element toxic or not is more than just its atomic number for example chlorine is very toxic but has a much lower number than gold that is for all porposes non toxic. What make somthing toxic is its chemical activity as determined by its valance or number of electrons on the outer shell of the atom.

drewgrey (author)2011-07-13

Great instructable. Bismuth would be a great material...except for the name...How about Shinyium

arizonadixon (author)2011-06-14

this is very cool but rapidly cooling the bismuth is counterproductive for crystal formation you wold get larger and more defined crystals if you cooled the bismuth slowly, the longer the cooling the bigger the crystals

zack247 (author)2011-06-13

how soft is this metal? as i was reading the ible i was thinking about making home made die cast cars or maybe even heatsinks for computers..

how does paint stick to it?

and i would consider possibly a 2 part mold or something, it may help with the oxidization if all that makes contact with the air is a part that will be cut off and remelted.

Void Schism (author)zack2472011-06-13

For casting I think it would be cheaper to use a casting alloy such as "white metal"... unless you want the unusual properties of bismuth such as it's diamagnetic effect.
For two part casting I recommend
Silicone RTV is lovely stuff to work with :)

aliencam (author)2009-02-05

An even better way to prevent oxidation would be to do this in a non-air atmosphere. You can accomplish this by using blocks of dry ice, around the bowl, this would remove a lot of the oxygen from the atmosphere around your experiment. You would have to figure out a way to keep the dry ice above or at the level of the rim of the bowl though, as CO2 is heavier than air. This would also allow you to get crystals of bismuth that wasn't oxidized, instead of the flecks and blobs that you would get by pouring it into water. the oxidized colours are part of what makes bismuth crystals awesome though, so why would you want to prevent them?

Dr. dB (author)aliencam2011-05-02

Interesting idea, but would have to use electric heating - that much CO2 would probably extinguish any flame-based system. Also, in a simple, "open crucible" design, upward convection would likely carry most or of all the CO2 away with it, leaving a "cold draft" of air in its wake, filling the crucible. Perhaps some careful mod.s to an old pressure cooker might yield a relatively-"sealed vessel" through which inert gas(es) could passed (maybe MIG/TIG welders' argon blends?) but, at these melting temp.s, you'd certainly want to keep safety and bursting-hazard issues at the top of your " keep a weather eye upon..." list....

violentorchid (author)2011-04-22

Just found this funny.
"Recently, however, it has been found to be very slightly radioactive: its only naturally occurring isotope bismuth-209 decays via alpha decay into thallium-205 with a half-life of more than a billion times the estimated age of the universe."
"Bismuth is the most naturally diamagnetic of all metals"

Good things to know.

rachel (author)violentorchid2011-04-22

Funny indeed! This kind of thing always makes me wonder, how did they figure that out? I mean, pretty sure nobody has got a chunk of bismuth sitting next to a Geiger counter just waiting for decay for even one universe-age, much less a billion!

wolfkeeper (author)rachel2011-04-23

Avogadro's number is really big (6 with 23 noughts after it), and so they can just wait for a few of the atoms to decay in a block, and detect that (either the radioactivity directly or the decay products). Shouldn't have to wait *too* long with a big enough block.

primadiana (author)2011-04-19

AWESOME!!! It is Moldable!!!! I was hoping it can be! YAY!!!

primadiana (author)2011-04-19

But I like the oxidiation!!! It's pretty!

hjjusa (author)2011-04-19

I just discovered the metals in nickels, dimes, quarters, half dollars, are very toxic. Also the ink in paper money, send it all to me and I will dispose of it in a bank and get rid of it with a debit card. lol

Exocetid (author)2011-04-17

The title of this Instructable, "Fun with Bismuth" reminded me of the fun we used to have with Mercury (that's right) back in HS. This was circa 1970. Back then there was a large brown bottle of it in the lab store room. We would pull it out and pour large pools of it into our hands and "play" with it. Much got spilt and flowed who knows where. Some no doubt went down the drain! This sort of silliness happened all over the country.

Now, of course, we know how unbelievably dangerous and toxic mercury is. I wonder how safe bismuth is? I am going to give this activity a bit of the "benefit of the doubt" and say that given the current state of our science, it is probably far safer to handle than good old Hg. That said, who really knows the long term effects? Keep in mind that this is a metal and it has some, shall we say, closeness to lead--and look what we now know about Pb.

Just take care--you don't want to be the poster boy someday for some peculiar Bismuth-caused cancer!

ELShaw (author)Exocetid2011-04-17

Actually, it's the fumes that are the toxic "dynamite" of mercury, something I found out precisely because I played with so much of it in my hands, just as you describe. Don't ingest or breath the stuff, and you'll likely be no worse for the wear. Wonder what substance we traffic in/play with now that in the future they'll discover is toxic? Ya pays yer nickle and ya takes yer best shot...

paqrat (author)ELShaw2011-04-18

Fumes are definitely toxic and including ingestion probably account for most toxic occurances. It can be absorbed through the skin though. One would have to handle a lot of it over a period of time. Many years ago Mercury was used in recovering the gold from ore. I remember reading where the Spanish would mix mercury with the ore then pour the amalgam over straw laid on the ground. They then used donkeys to walk around over the straw. The mercury was absorbed by the straw and, unfortunately for the donkeys, their hooves. After losing too many donkeys the Spaniards switched to something less expensive and found in greater numbers; Native American slaves. I also read that in a smaller production, perhaps a pair of gold prospectors, they would also use mercury mixed with the gold ore in an amalgam. Then they take a potato and pour the amalgam into the potato. The potato would absorb the mercury and other impurities leaving flakes of gold. And if one wished to rid oneself of a partner one served the partner a baked potato made from the mercury laced potato. The Mad Hatter in Alice in Wonderland was based on a true phenomenon, that of hat makers with various neural problems including death. I believe this was caused by use of mercury in the felt making process. Whether the exposure of the hatters was due to fumes or by handling the felt I do not know.

When I was in High School science class we had small quantities of Mercury that we "played" with. I can remember pushing a small bead of the stuff back and forth in the pencil depression on the desk. I've lived almost 50 years since then with no known neural problems so I think exposure would have to be considerably more than what I experienced.

Exocetid (author)paqrat2011-04-19

The Mad Hatter was indeed predicated on the mercury poisoning that hatters (makers of felt hats) would get from their profession. It was also a hazard faced by early photographers making daguerreotype plates, the developing of which required exposure to a heated mercury vapor in a dark and enclosed space!

Ingestion, either by mouth or vapor, is what gets you. Over indulgence in predatory fish may also get you as mercury accumulates in their bodies.

As I stated earlier, i too "played" with Hg back in the day. The senior moments are increasing in frequency now and I wonder if the onset might have been delayed a bit had I not played with quicksilver back then.

Exocetid (author)ELShaw2011-04-17

These things always remind me of the funniest movie ever produced, and that would be (drum roll)...Woody Allen's "The Sleeper". In the movie Woody is a Californian sixties hippie health food store owner who goes to the hospital to have minor surgery and winds up being frozen. He is unthawed in the far future to a totalitarian regime and is "rescued" by the resistance. In one seen they offer him cigarettes and twinkies explaining that science discovered that they are very healthy and prolong life!

paqrat (author)Exocetid2011-04-18

I think Woody's funniest movie was "What's Up, Tiger Lily" . The first 4 or 5 times I saw it I laughed so hard I had tears running down my cheeks.

hmmm also loonk how close to lead that gold is, one proton...yet gold is 100% non toxic, if you eat it, your body just passes it...just a random thought

I count three protons difference. In between are mercury and Thallium, both of which are quite toxic...

Well, of course you cannot predict chemical behavior just on proximity of one element to another on the PT--I'm just sayin'...

uglymike (author)Exocetid2011-04-17

Actually with the discoveries of the toxicity of lead, Bismuth has been used as a substitute for some commercial products. (I know I've see it used in shotshells where lead ammunition is outlawed.) It's been part of the main ingredient in Pepto-bismol for almost 100 years and is used in other medicines and cosmetics, so it has a fairly long track record of safety. Though not "non-toxic", bismuth needs to be taken in fairly high doses over a along period of time (think bottle of the pink stuff every day for a month) before adverse reactions begin, and is considered reversible (unlike Lead and Mercury poisoning).
So while Bismuth is not "completely" safe, it is no more dangerous than most over-the-counter medication. Use with care.


Exocetid (author)uglymike2011-04-17

Please proceed with caution. Pepto-Bismol contains bismuth subsalicylate, a compound containing bismuth. What you are saying is not unlike saying that sodium and chlorine are perfectly safe because humans have been ingesting sodium chloride for millennia.

I personally would be very, very careful with melting any metals, including gold (if I had some!!!). I am not saying don't do it, just be careful. We live much longer now and even short encounters of alien substances with tissue may lead to dramatic and undesirable consequences later.

Science is fun, just play safe.

spiralc (author)2009-02-11

!!!!! bismut is poison. It is heavy metal and it will store itself in your body. When you melt it, you will inhale its vapor, if you cut it, there will be small particles. I am also a lot into bike frames, and there are types that are made with bismuth. There is warning not to cut, drill or weld this frames.

ducktape.mac (author)spiralc2011-04-18

it's none of your bismuth whether or not people drill it!!!

...never mind.

tyty100 (author)spiralc2011-04-18

no its not
just because it is a heavy metal and is close to lead on the periodic table doesnt mean it is poison or toxic
look at gold because it will just pass if you eat it and there are no deadly vapors if melt

also there is not such a thing as bismut, just a typo
get ur facts strait

Spokehedz (author)spiralc2011-04-17

There is nothing wrong with Bismuth. The MSDS sheet says so.

twallace-1 (author)spiralc2011-04-17

Bismuth is the main ingredient in Pepto Bismol, so I'm thinking it may not be poisonous!

absolofdoom (author)twallace-12011-04-17

Peppermint is actually poisonous, you know. Just because a small amount of it isn't toxic, doesn't really mean anything.

bobbym529 (author)spiralc2011-04-17

You may be thinking of beryllium. That has all the cautions you list and is used in bike frames and golf clubs.

_soapy_ (author)spiralc2009-03-05

Seems very unlikely that anyone would use bismuth, a low temp, soft and brittle metal which is very heavy, in a bike frame. Are you sure?

siphio (author)spiralc2009-02-15

Bismuth *is* a heavy metal, but as the Instructable says, the toxicity is somewhat lower than lead - in fact, it's commonly used *instead* of lead since the toxicity of lead has come to be better understood. More info at wikipedia including it's use in cosmetics and an ingredient in pepto-bismol :).

WillyTheKid (author)2011-04-18

holy long link. in essence, this book is saying that if you let the bismuth cool until a crust forms on top (impurities with a higher melt temp cooling) and then poke a couple holes in the crust and pour the liquid (pure-ish) bismuth out, and then let it cool very slowly and don't move or jar the liquid as it cools, in theory you should end up with almost pure crystal. it's actually a little more complex than that but that should help.

Let me know how this works out. Taking Materials Science this semester. Love it! I may suggest this as a lab to my professor depending on your results.

patenaude (author)2011-04-17

Have you tried to polish the hearts? I think you might get some of the artifacts of the mold off.

The oxidation swirls make me wonder if you can anodize it, the way you can anodize titanium.

- Mitch

St Jimmy (author)2011-04-17

My friends used to do this all the time in tech, when we had finished electronics or pouring pewter into molds, we got a bucket of water and poured the rest in. Makes some interesting shapes

___ (author)2009-02-25

This reminds me of a victorian bar trick that i read in a book made in 1890. You would make an alloy wih bimuth tin and lead and make into a teacup. as soon as u poured something hot into it t would melt. now we know better than to have lead in our tea!

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