Biting Gold

Hi everyone, welcome back to Cody’s Lab! So, a long time ago back when I did my biting indium video a lot of people posted comments saying that I should try biting some gold. because, apparently, one of the things people do in order to confirm that gold is authentic is to
take a bite out of it. You can see this quite often in photos
of Olympic gold medalists of noshing down on their Olympic awards. And as it
happens I just bought a one ounce gold bar using my last paycheck and so I
thought why don’t I give it a shot and see if I can determine it’s authentic? Well first of all came with an assay
certificate so I’m fairly certain came from a reputable source but I’d also gone through the trouble of measuring its density and it does have the correct density however there could be a tungsten core
in here, right? I doubt it because it’s so thin, I mean, someone probably wouldn’t go through the trouble of putting tungsten core in a bar this size but if there is tungsten there the gold
would be very much harder than would be normally. Got a piece of tungsten here. Tungsten is a very hard metal but gold is a soft metal. I don’t think I could dent that with a pair of pliers. So let’s try biting this bar and see what happens so I was only able to dent it just very
slightly there’s definitely a dent there but it’s
nowhere near what most people would expect so does that mean that this bar
is fake? So to find out how about I take a piece of gold that I know to be
absolutely genuine because i actually refined this myself – thinking episode two
or three of my refining series. But anyway this is pure gold so let’s take a bite out of this and see
if it has similar results yeah, I’d say that bite mark is almost
exactly the same size so that means the gold bar is actually genuine ’cause they were about the same when I bit them. See a lot of people think that gold is very soft
metal almost like butter where as it’s actually about as hard as
aluminum. You can see this aluminum muffin tin that I cut apart. If I take a
bite of aluminum You can see that i get about the same size dent. Gold is a soft metal compared
to steel or tungsten but it is actually quite hard compared to a lot of other metals
such as lead or, of course, indium but I was actually able to put a small dent in this
gold so perhaps it is a good method to determine if it is genuine or not so i have this gold bar here which is actually a fake fake gold bar that I bought off eBay. This is supposedly contains a thin coating of gold on the surface but it actually
doesn’t even have that it’s solid aluminum-bronze. I even cut corner off of it to do further tests and I’ve confirmed there’s absolutely no gold and these things are all over eBay
so watch out for them but let’s take a bite of this. You see I have dented it vary slightly but it’s much less than the gold is dented. That’s
because aluminum-bronze though having a gold color to it is quite a bit harder.
Now Olympic gold medals are actually a thin
coating of gold over pot silver so let’s think about the silver bar here to see
what kind of dent it makes if that’s the case ok so just slightly larger than the aluminum-bronze.
Silver and copper are about the same hardness. Here is a gold coin which I’ve
actually made and is fake this is a piece of steel coated in 24
karat gold you can easily determine that this is fake just by bringing a magnet near
it but let’s also try the biting test Yeah, there’s no way I’m denting steel. There is one way, of course, that I can soften gold. This gold bar has been worked hardened. The act of punching it into the bar
shape has actually hardened the metal See because it puts strain in the crystals
of the gold and it increases the strength of the material, but if I heat it up I
can relieve that strain and the gold will return to its softened state. So let’s actually do that and see if it makes any difference to how it is with biting it. There we go. I heated the gold up till
its a bright red hot which is just a little bit below its melting point so
that I don’t have a puddle of gold on my hands and I now as I let it slowly cool off it should form the unstressed crystals
of the soft gold. This is of course another way you can determine the gold
is genuine because a gold bar that is fake would oxidize. Gold does not oxidize even
at high temperatures so if i take this fake gold bar here and do the same thing to it. You can see that the bar is actually severely discolored now. In fact just as I’m holding it you can see it oxidizing in the air It’s forming the copper oxides.
I need to find somewhere to put this. There we go. This gold
bar has almost cooled down to room temperature. So another cool thing about gold is it cools off very quickly. Let’s take another bite out of this and see if
there’s any difference Oh yeah most definitely. I was able to take a much larger piece out of that. I wasn’t able to bite it off at the dent is like 10
times bigger and finally I have here some gold dental crowns that fans sent
me using the address in my about section on YouTube. This is actually the biggest
donation I’ve ever gotten to my channel because these weigh about 4 grams each and they’re about 60-percent gold with the balance being silver, copper and palladium. That fan wishes to remain anonymous but if you’re watching thank you very much i’ll
definitely be putting to use my videos but what I have them out for is the fact
that gold when alloyed with some other metals actually becomes quite hard and
you can take advantage of its properties where it’s inert and
it actually makes very good dental material so you can bite gold or you can
bite with gold. So hope you all enjoyed I’ll see you next time. Now that I’ve softened the gold bar by
heating I should actually be able to bend it just with my hands and indeed I
am So I’ve pretty much ruined this bar now but It’s still valuable due to its weight I
just can’t sell it for the coinage premium.

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