# Casting a 2tonne block of gold (yes I said 2tonne)



## Anonymous (Jul 10, 2010)

I am a prospective author researching for my first novel. The plot requires that my characters dispose of two tonnes of stolen gold. UK law on treasure (treasure trove) states that gold or silver buried treasure of artistic or historic value is the property of the Crown (these days the UK government), but that the finders and the property owner where the find is made are rewarded at full value. There are lots of rules to follow and it takes about two years but it would provide a way of turning the gold into cash at full value and tax free. Obviously turning up with several hundred ingots bearing the stamp of a mining company that has just had several hundred ingots stolen from it is not very clever, so my characters propose to convert the gold into a 10th century religious alter. They then pretend to find it, hand it over, and claim the reward. Of course they will firstly adulterate the gold with some copper and silver to simulate the degree of refining available in the 10th century. At first I had thought of them creating Saxon jewellery or Spanish Doubloons but the conversion process would be too complex and time consuming, and the fakes too easy to spot. A massive find on this scale would create so much infighting amongst the academic community that they just might loose sight of the fraud, as they did in the case of Piltdown Man.

I need help on the following technical points.
Can a large casting be created by pouring many shots into the same mould? The casting process may be spread over several weeks.
Would the metal fuse together to form single block or would the separate pours just split apart easily? 
Typically 10th century gold would be approximately 21-22 carat because the technology did not exist in Europe to refine it further. The various pours would have slightly different amounts of impurity as there would have been no way to measure or to make them consistent.
Did better refining techniques exist in Central America around the same period? 
What is the biggest gold cast ever made? by who? when? how?


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## goldsilverpro (Jul 10, 2010)

If my math is right, two metric tons of pure gold would only be a cube 18.5" (47 cm) on a side and 21-22K gold would be a little bigger. Not too big for one pour, I would think, with the right equipment. Maybe they could get in cahoots with the owner of a big foundry. I have known companies that shut down their plant for 2 weeks and everyone takes their vacation at the same time. That might be a good time to do it.

Except for the impurities, once the gold is melted, it loses it's identity. I once heard about a refiner that bought (for a song) 2 very hot 18K chalices stolen from a church that weighed several pounds each. Within minutes of buying them, they were in the furnace.

Some old bronze sculptures I have seen were cast in pieces and then attached together with some type of fastener.

Alec Guinness in "The Lavender Hill Mob" cast the gold into Eiffel Tower souvenirs (and painted them black, I seem to recall) and tried to smuggle them out of the country.

It would probably be smart to get several samples of real 10th century gold and have it analyzed for the impurities. Then you would have a better idea of what to add to the stolen gold. 

If I owned a large mining company, I might add to the gold a few ppm (in exact quantities) of some oddball metal that would never be found in gold (if one exists), to act as a tracer. Maybe, that's how your thieves could end up getting caught 

If you could get the gold to a place without many gold regulations, like the US, you could open up several scrap jewelry buying locations. Then, you could alloy the stolen gold to about 12K and ship a little here and a little there to refiners along with the scrap you were buying.

Maybe they could get in cahoots with a huge scrap buyer like cash4gold and shuffle in the stolen gold. Someone like that slimy looking guy that runs cash4gold would surely jump at the opportunity. Of course, they would certainly get screwed and would be lucky to end up with 10 cents on the dollar. 

I would guess that making multiple pours into one casting would tend to separate between layers, especially if the gold wasn't pure.

Our resident gold caster, 61 silverman, should chime in on this.


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## Lou (Jul 10, 2010)

What a fun notion! Surely, if one could smuggle 2000 kilograms of gold, one could find a way to "launder it". 

Personally, if it were me, I'd just build myself a nice propane-air fired furnace add some scrap platinum to it and keep the alloy at 20K. This is a beautiful bronze-looking material, except considerably heavier. Then I'd go to or start a bell foundry and make myself a nice "bronze" bell to go with the beautiful boat I'd buy for myself. I could then sail away into the sunset quite happy. I'd probably also do some nice lost wax castings of gold ornaments for my yacht  

A gold altar of that size would be something suspicious, I would think. At least coming from the 10th or 11th century before large foundries were established. You'd need one hell of a crucible to hold that much mass, and you can't cast it piecemeal, it will separate, especially if it is not pure (an oxide layer will form as it cools). 

Much better would be a trove of Atocha-styled gold ingots and rounds/pucks buried as pirate's (or even a duke or lord's personal treasure from the Spaniards) hidden in some cache out in the somber British countryside.


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## Barren Realms 007 (Jul 10, 2010)

Will this help?

http://www.panama-guide.com/article.php/20060427223159815


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## Hephaestus (Jul 10, 2010)

Wow. What writers do while researching.

I never casted gold, only Al, but a 2 ton gold cube would need a 50 cm side cube crucible to melt. Only a reverb furnace could do that. With a good insulation and some oil burners maybe at once. :|


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## nickvc (Jul 13, 2010)

Anything claiming to be that old would go to the British Museum for authentication and valuing so I fear your idea is dead before you start,as to the idea of alloying the metals this has been done before with the Brinks haul by rumour...


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## Irons (Jul 13, 2010)

Even matching the alloys to those found in ancient artifacts wouldn't work unless you can match the isotope ratios as well.


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## lazersteve (Jul 13, 2010)

One way to make it appear old is to dope the gold with the powdered form of something that is very old.

Steve


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## nickvc (Jul 13, 2010)

I had a customer that had 3 or 4 Kilos of 17th century dutch spoons and forks which I had to melt into an ingot in a new crucible,this I gather was then sent to an outworker to be rolled into sheet don't know what was made but it would pass metallurgical examination into the provenance of the silver :roll:


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## Anonymous (Jul 14, 2010)

Thanks for the feedback. 
Firstly I am writing a novel here, not a manual on how to launder gold. 
I want to make it as authentic as possible and find out what is practical, but the best bit of a writing novel rather than a technical manual, is that I can use poetic licence. (Although in my day job as an industrial design engineer, I find that 'poetic licence' does occasionally appear in tech. manuals) 

In my plot stealing the gold is the easiest part, more a matter of being in the right place at the right time. It sets a background for the nub of the book which is how to get away without being apprehended. Laundering the gold needs three criteria. 1 It should be done in secret so that you don't get caught, that implies avoiding other criminals, fences and the like. When it comes to getting rid of that much gold the best place to hide is in plain sight. 2 You need to get it past the tax-man so that you can openly spend the proceeds. 3 You want to realise maximum value. Full value or if possible a premium for giving it artistic/historic merit. The Treasure Valuation Committee in the UK is supposed to apply "market value" to items it assesses. 
I chose to cast a single item because there is nothing to compare it against. All old coins have some wear, or were stamped in different places, using different dies. To effectively reproduce those conditions would be very time consuming and expensive. The same would apply to jewellery or chalices and plate. You then have to sell it and explain where you got it against a background of approximately the same amount of gold having gone missing. Carating down from 24ct has the added advantage of disguising the actual quantity. 

The answer to my primary question, can you cast it in multiple pours is no. So I now have two supplementary questions.
How could my characters cast it in a single pour? (see question on reverb furnace or other suggestions)
A plausible explanation of how someone in the 10thC could cast it in a single pour 

Steve, interesting thought. That sort of substance do you have in mind? Nothing organic will survive past melts temperature so carbon dating is out. I have arranged for some pieces of bog oak from Ireland to be discovered at the find site, to suggest an origin for at least some of the gold.

What is a "reverb" furnace? where would I get information on building one? My characters would use propane as the heat source and in the UK it comes in 47Kg cylinders. With four high pressure burners a cylinder will last 5.2 hours, and doing the calculations there is enough energy in a single cylinder to melt the gold if the heat transfer efficiency is only 17%. I have no experience no casting which is why I'm asking you guys. 

The comment on isotopes is valuable and I will research it further, but my first instinct is the omit this from the text so that any real thieves who don't do their own research are looking at 20 years. Collecting that much gold in one place in the 10thC would require getting it from many places, so the isotope ratios would be totally screwed up anyway. One of the plot arguments against the alter being genuine is who in history could have amassed so much gold, and why no documents or rumour of it survives. 

I know it would go immediately to the the British Museum for authentication before being passed to the Treasure Valuation Committee. Given the nature of the find it would probably be evaluated by several other academic institutions as well. A major sub-plot of the book is the reaction it would get their and the interplay between "the sceptics" and "the academics who want to believe" that this could have been made in the 10thC. That is one reason for needing arguments for and against. Forensic examination has moved a long way since the British Museum agreed that Piltdown Man was authentic, but even they are fallible. 

Some technical points that I have already worked out. 
The mould would be made using techniques described by Roger of Helmarshausen a Benedictine monk/metalworker in a book he wrote sometime between 1110 and 1140 (Fortunately already translated from the medieval latin)
The master pattern would be a timber case covered in lost wax. Beeswax for authenticity
Traces of the burnout would be left in the mould to find their way into the casting (my Irish bog oak again)
The mould would be a clay pit using local clay from the find site.
Any alter of this date (some much smaller ones do exist) would have exterior decoration applied. Champleve or Basse Tialle which are enamelling techniques similar to Cloisonne but using recesses rather than raised cells are my favoured options. I have research enough about the composition of the enamels used at the time to make this look authenic.


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## Irons (Jul 14, 2010)

The beeswax would fail the Carbon 14 test for age.


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## glorycloud (Jul 14, 2010)

OK, I can't stand it anymore. It's altar, not alter!!
We "alter" gold in powder form with heat into gold in metal form.
(Well at least some people can. 8) )

An altar is a place of worship or sacrifice like the altar of incence
found in the temple in the bible. See Exodus 30:1 or just take
a walk through the book of Genesis where there are many, many
references to "altars".

Thank you. I will get off my soap box now.


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## Irons (Jul 14, 2010)

glorycloud said:


> OK, I can't stand it anymore. It's altar, not alter!!
> We "alter" gold in powder form with heat into gold in metal form.
> (Well at least some people can. 8) )
> 
> ...



The whole point of this discussion was to alter the Gold. :mrgreen:


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## goldsilverpro (Jul 14, 2010)

> The whole point of this discussion was to alter the Gold.


What would we do without you, Irons?


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## nickvc (Jul 14, 2010)

goldsilverpro said:


> > The whole point of this discussion was to alter the Gold.
> 
> 
> What would we do without you, Irons?


Love it...haha


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## Irons (Jul 14, 2010)

goldsilverpro said:


> > The whole point of this discussion was to alter the Gold.
> 
> 
> What would we do without you, Irons?



Probably live a few years longer. :mrgreen:


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## Chumbawamba (Jul 14, 2010)

At the risk of suggesting an entire plot re-write, one which is much simpler as well, I propose the following:

Everyone is wary of gold-plated tungsten bars, but who would ever suspect tungsten-plated gold bars?

Have the crooks disguise the gold as a shipment of tungsten, filling out the pallet with whole tungsten ingots as necessary.

Once on the other side, the tungsten is stripped in an acid bath and voila: 2 tonnes of smuggled gold.


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## Anonymous (Jul 14, 2010)

Thank you Irons, I have just looked it up and an Accelerator Mass Spectrometer can get a result from 1-2 milligrams so that requires a rethink.
The Saxons used to etch their gold to enhance the yellow colour. I will research what type of acid they used to see if that will remove traces of beeswax without leaving a residue that could be as easily dated. 

I will have to go back through this discussion and alter alter to altar. I consider my hand slapped and am hanging my head in shame as I write this. Stay on your soapbox, I like pedants. I am one myself.


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## glorycloud (Jul 14, 2010)

Hey Irons, should I be wanting to fight this guy for calling me a pedant? :lol:


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## goldsilverpro (Jul 14, 2010)

> The Saxons used to etch their gold to enhance the yellow colour.



It's called depletion gilding. Still used today.

http://www.google.com/search?hl=&q=depletion+gilding&sourceid=navclient-ff&rlz=1B3GGGL_enUS259US259&ie=UTF-8


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## Irons (Jul 15, 2010)

glorycloud said:


> Hey Irons, should I be wanting to fight this guy for calling me a pedant? :lol:



Some Viagra will take care of that. :twisted:


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## Irons (Jul 15, 2010)

goldsilverpro said:


> > The Saxons used to etch their gold to enhance the yellow colour.
> 
> 
> 
> ...



I found this in the .pdf:

Sometimes exposure over long periods of time to salts and corrosive chemicals in the
earth may cause a depletion gilding effect. Maryon writes: "It has been observed that
when objects made of gold have been buried in the earth for many centuries a change
occurs in the metal near the surface of the work. Much of the alloying metal, be it copper,
silver or some other metal is dissolved by the chemical action of the damp earth leaving a
thin film of almost pure gold at the surface of the object "(Maryon, p 8). This
observation, however logical seems to me not to take into account the possibility of the
makers having deliberately performed a depletion gilding procedure on the metal.


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## Irons (Jul 15, 2010)

Irons said:


> goldsilverpro said:
> 
> 
> > > The Saxons used to etch their gold to enhance the yellow colour.
> ...



This is like the 'halo effect' that many metal detector users are familiar with. The base metals migrate into the earth in contact with the object, causing a localized increase in conductivity.
This phenomenon might be difficult to replicate.
The object would also have to be buried in a strata that matches the period the artifact was supposed to originate from.


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## patnor1011 (Jul 18, 2010)

This looks like way too much research for a novel. I wonder if I will not see an article in Sun or Mirror in next few months about some major discovery by happy amateur metal-detector-archaeologist somewhere near Gryn Goch... 
That Irish bog oak I can send you few pounds if you want... :mrgreen:


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## joem (Aug 8, 2010)

Hello
I can't answer on refining but I can give you thoughts on plot.
If the crooks are smart enough to steal 2 tonnes of gold which must have some sort of security envolved why go to the effort to just claim a reward? In todays value the gold is obviously worth more. To go to the effort to make an Altar why not make something more interesting that can create police vs crimal tension, may mould it into a truck body and try to drive it out of the country to an international buyer, or air craft wings and try to fly it ... yada yada yada you get the idea twist it up and ad some unbelievable excitement.
my thoughts


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## butcher (Aug 8, 2010)

that plane may not fly, gold is heavy. :lol:


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## joem (Aug 8, 2010)

butcher said:


> that plane may not fly, gold is heavy. :lol:


depends on how big you make it
retrofit a cuurent plane, hey if they can steal a two tonne block maybe thay have some monetary backing from interested parties.


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## patnor1011 (Aug 8, 2010)

Well that robbery actually happened in UK. Most of the gold stolen was never recovered. 
http://en.wikipedia.org/wiki/Brinks_Mat_robbery


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## Irons (Aug 8, 2010)

joem said:


> Hello
> I can't answer on refining but I can give you thoughts on plot.
> If the crooks are smart enough to steal 2 tonnes of gold which must have some sort of security envolved why go to the effort to just claim a reward? In todays value the gold is obviously worth more. To go to the effort to make an Altar why not make something more interesting that can create police vs crimal tension, may mould it into a truck body and try to drive it out of the country to an international buyer, or air craft wings and try to fly it ... yada yada yada you get the idea twist it up and ad some unbelievable excitement.
> my thoughts



James Bond 'Goldfinger.'

Gold was smuggled by making it into car parts.


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## joem (Aug 8, 2010)

Irons said:


> joem said:
> 
> 
> > Hello
> ...



Amazing enough, I have not seen gold finger
I plan to purchase all the bond movies at some time in the future
sorry to copyright owners for idea infringments - lol


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## Anonymous (Aug 8, 2010)

Author, 
I can think of many,much simpler,ways for our crooks to get the full value for their new find.
I think the problem is that you are not thinking outside the box.You are going on the premise that the government will ultimately end up with the gold.Why not use a method that bypasses the government all together,like lou suggested.I love the bell idea,however most sailboats have thousands of pounds of lead in them used as counter-balances,why not just replace that with the gold.
Another idea I had would be to melt the gold into ingots,weighing maybe 50lbs each,have one of the members travel out of the country,then purchase the ingots as fishing weights?Then simply mail all of the gold right under the noses of everyone.Of course they could always alloy the gold,or dip it, to give it the appearance of lead.Then simply cupel it on the other side.Another Idea would be to make rods,and sell them as welding rods.A million ideas come to mind.
I know it is not what you were looking for,but the idea is to figure out a way to get the full value for it,and you have to remember that our crooks are going to be thinking about an idea day and night.Every waking moment will certainly be spent thinking of a pheasable plan to get their hard earned money and all of these ideas will be very easy,and fast,to make,compared to an altar.
I have a couple of other ideas,but this reply is too long as it is.
If you still insist on going with the altar idea,you can always talk to one of our members mark who made a 125+pound sculture of mickey mouse out of 24k gold.
Check this out http://goldrefiningforum.com/phpBB3/viewtopic.php?f=67&t=6428&p=57655#p57655


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## goldsilverpro (Aug 8, 2010)

Awhile back, there was a series on 101 network (Direct TV) called "Smith". On one episode, they had a bunch of stolen stamped gold bars that they wanted to remelt to change their identity. They also added a little scrap copper that they found laying around to change the makeup a little. They had a real brand-new commercial crucible furnace (I would guess its size was about a #40) in an old barn for the melting. The actual melting was really phony. There was no roar and no bright yellow color in the furnace to indicate it was even heated. They obviously burnt some paper in the furnace to simulate a little smoke. I watched it a second time and listed about 10 stupid things they had done wrong, from start to finish. The consultant they used for this must have been an idiot. Either that or the people in charge cut corners because they thought the viewers were idiots and wouldn't know the difference (this idiot did!). I was going email the errors to them but never got around to it.

After melting, they cast (they didn't show much about how they did the casting) it all into hand tools, such as large wrenches, painted them black, and put them in a big tool box on a truck. Do you know anyone that paints their tools solid black? Also, just putting them together in a box would rub off some paint and expose the gold. Were it me, I would have heavily nickel plated the tools and then done something to make them look used - scratch them a bit and wipe on some dirty grease, maybe. The nickel could easily be removed with nitric at a later date.


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## Irons (Aug 8, 2010)

The Italian Job(New Version)

Crook sells minted, easily identifiable Gold Bars to the Ukrainian Mafia who run a scrap yard.

One way or another, you pay a tax, either to the Govt, or the middle man. Nobody goes home hungry.


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## joem (Aug 8, 2010)

ok out of the box (or out of my mind) AR in a coverted apple factory and rebottle in glass bottles ( organic juice) for export?
or cow urine bottles for homeopathic cure all - they can even name it Urine-Aid - The Yellow Gold Cure


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## Chumbawamba (Aug 10, 2010)

I thought my tungsten plated gold bars idea was clever (and timely even) but it appears to have flown over everyone's head. Oh well.


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## HAuCl4 (Aug 10, 2010)

Inquart with copper and make electric cables in rolls. Ship by container. Ready for private nitric acid swimming pool at destination, or refine as needed for expenses. Keep it simple. :idea:


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## Barren Realms 007 (Aug 10, 2010)

HAuCl4 said:


> Inquart with copper and make electric cables in rolls. Ship by container. Ready for private nitric acid swimming pool at destination, or refine as needed for expenses. Keep it simple. :idea:



I would like to see the drop on that one. 8)


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## HAuCl4 (Aug 10, 2010)

Barren Realms 007 said:


> HAuCl4 said:
> 
> 
> > Inquart with copper and make electric cables in rolls. Ship by container. Ready for private nitric acid swimming pool at destination, or refine as needed for expenses. Keep it simple. :idea:
> ...




Me too!. Purchase 6 tons of lead ingots for export, and mix the gold in there before shipment by container, that's even simpler than the electric cables. Many ways to skin that cat...I wish I had that "problem". :lol:


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## rewalston (Aug 10, 2010)

Chumbawamba said:


> I thought my tungsten plated gold bars idea was clever (and timely even) but it appears to have flown over everyone's head. Oh well.


Sounds like a good idea to me, after all they tried gold plated tungsten to fool everyone into thinking there was a lot of gold in the vaults.


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## goldsilverpro (Aug 10, 2010)

Chumbawamba said:


> At the risk of suggesting an entire plot re-write, one which is much simpler as well, I propose the following:
> 
> Everyone is wary of gold-plated tungsten bars, but who would ever suspect tungsten-plated gold bars?
> 
> ...



Pure tungsten plating is very difficult to do. Like aluminum, pure W can't be plated from an aqueous (water-based) solution. It can be deposited as an alloy (e.g. Ni/W). It could also probably be evaporated or sputtered. It must be plated from an organic or fused salt system. A search revealed no pure W being plated commercially. All I found was lab experiments.


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## Chumbawamba (Aug 11, 2010)

Sure, but it only has to LOOK like tungsten.  It'll still weigh correctly


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## goldsilverpro (Aug 11, 2010)

I would say that nickel looks like tungsten and it's a lot easier to plate.


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## Harold_V (Aug 11, 2010)

goldsilverpro said:


> I would say that nickel looks like tungsten


Not in my experience. I've machined a fair amount of tungsten (not a fun job). It's a dull gray color, very unlike nickel, which has a distinct yellow cast. Allowed to age, tungsten has a totally different appearance.

Harold


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## eagle2 (Aug 24, 2010)

Lol, :lol: I sure like the idea, about making a fake `brass bell`, for my boat. Keep the story simple and put more girls in it. Of course, any novel I wrote would be simple and short. :mrgreen: 

Al


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## geonorts (Oct 9, 2010)

Gold produced by mining companies is usually gold Dore, often of a lower purity from 40-80% Au with Ag, Pd, Pt... etc depending on the mine. This is usually sent off to refineries and then sold. I've heard rumours that some mines would get 1-2 armoured vehicles pretend to load them and send them off when in fact the gold is put into a car and casually driven to the refiner. Just a thought


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## Fournines (Oct 9, 2010)

goldsilverpro said:


> After melting, they cast (they didn't show much about how they did the casting) it all into hand tools, such as large wrenches, painted them black, and put them in a big tool box on a truck. Do you know anyone that paints their tools solid black? Also, just putting them together in a box would rub off some paint and expose the gold. Were it me, I would have heavily nickel plated the tools and then done something to make them look used - scratch them a bit and wipe on some dirty grease, maybe. The nickel could easily be removed with nitric at a later date.



I know of someone who was doing just that. They molded common items and painted them to pass through customs. Got caught, spent some time in jail.


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## T3sl4 (Oct 9, 2010)

Hmm, even if you could plate tungsten, it obviously wouldn't have a sintered structure (probably the main reason it has a gray color). That suggests, then, taking standard tungsten forms (bar, rod, etc.), hollowed out, and filling them with gold. For example, a cylinder could be bored, a gold plug inserted (or poured in place), and a shrink-fit tungsten plug tapped into the remaining headspace. Done correctly, there's very little airspace remaining, the integrity is almost metallurgical, and it's very difficult to detect (assuming you machine the mating surfaces to hide the seam).

Once complete, by melting the gold inside, it would probably braze to the tungsten, which would allow a metallurgical bond, though it may seep through the pores and the remaining seam, providing some evidence. A simple press fit setup may be better.

As altars go, it's a wonderfully outlandish plot element, but as has been mentioned, it has a lot of problems, too. Some, like materials in contact with the altar, could be addressed; for instance, it might've been buried in a tomb instead, soil not touching the metal directly. This creates other problems, such as finding an undisturbed, period-correct tomb to hide it in (without disturbing anything, especially the entryway), or worse yet, trying to create one from scratch. Maybe it would be appropriate that the protagonists run across just such a find, I don't know.

Tim


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## Ocean (Dec 19, 2010)

Maybe some of us need to write our own books. :roll: 

Sounds like his plot has more opportunity to capture the interest of his target market than some of the proffered simplified/technically correct ideas.


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