# Gold tarnish problem



## mr-fixit (Sep 20, 2011)

I've Been making 1g globules of gold from a 24 carat bar. I cut 1g from the bar then melt it with a butane torch on a stainless steel plate. The problem is some of the globules are discoloured on top where the flame hits the metal, but the under side remains ok. Why is this and how do I rectify it?


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## mr-fixit (Sep 20, 2011)

In addition to the above post.

If I turn the globule over so that the tarnished side faces down and the normal side faces up then re-melt, the tarnished side goes back to the top where the flame is and the underside is normal. There must be a simple answer.


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## goldsilverpro (Sep 20, 2011)

You've contaminated the gold with iron, etc., from the stainless. Gold alloys readily with iron. The discoloration on the top surface is oxidation of part of those contaminating metals. The top surface is exposed to the air and/or oxygen from the torch. If you used a reducing flame, you might not see the contamination but it would still be there.


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## TXWolfie (Sep 20, 2011)

Ok will he have to add borax and use a crucible for this or am I wrong


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## mr-fixit (Sep 20, 2011)

What type of melting platform does not contaminate PM,s


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## jimdoc (Sep 20, 2011)

A melting dish.

http://www.contenti.com/products/casting/170-710.html

Jim


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## goldsilverpro (Sep 20, 2011)

mr-fixit said:


> What type of melting platform does not contaminate PM,s



Fireclay, clay/graphite, silicon carbide crucibles. Any of the jeweler's melting dishes. Soft firebrick that has had an indentation scooped out with a spoon. NO metal!


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## TXWolfie (Sep 20, 2011)

TXWolfie said:


> Ok will he have to add borax and use a crucible for this or am I wrong



As goldsilverpro stated the gold was contaminated by something not gold. From reading many posts on this forum you will probably need too drop it in acid to pull the gold, then drop it out of the solution, remelt in a clay crucible. My previous statement, please excuse what I typed. I was in the middle of a conversation and what my fingers typed was not being said in my brain to type (brainfart). There is alot of posts on how-to's you just have to find one and go step by step. Since I am fairly new to this and reading alot and watching video's this is what I would believe is needed to be done, but there could be an easier way. Hang in there and there might be an answer from a more knowlegeable person. Just trying to help out on the forums.

Rich


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## mr-fixit (Sep 20, 2011)

So its possible to decontaminate my gold. Could someone put me in the right direction, bearing in mind I am new to this.


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## Palladium (Sep 20, 2011)

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=61&t=5204&p=44752&hilit=contaminated+gold+borax#p44752


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## Geo (Sep 20, 2011)

exactly, dissolve the contaminated gold and re-refine it if you are concerned with purity. borax in addition to a form of lubricant for you crucible/melting dish is also for removing surface impurities that may occur from a dirty torch tip or carbon from the fuel like acetylene will cause.


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## TXWolfie (Sep 20, 2011)

woohoo I answered it correctly, I feel so proud of myself. I would pat myself on the back but to busy typing. :lol:


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## mr-fixit (Sep 20, 2011)

This may be very silly.
Could I clean the surface with sulfuric acid, re-melt clean etc until the cotamination has gone?


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## Geo (Sep 20, 2011)

sorry. the discoloration you see is just the reaction of oxygen on the surface of the metal. the contamination is all the way through the piece. melted gold will alloy with almost any metal and acts like a solvent so when the melted gold touched the steel it pulled the steel into the matrix.


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## TXWolfie (Sep 20, 2011)

Geo said:


> sorry. the discoloration you see is just the reaction of oxygen on the surface of the metal. the contamination is all the way through the piece. melted gold will alloy with almost any metal and acts like a solvent so when the melted gold touched the steel it pulled the steel into the matrix.


Wow I guess I am learning I was gonna say the same exact thing.


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## mr-fixit (Sep 20, 2011)

Er............em
I started with 1g of 24k and the end result is a 1g button. So its purity must be high, 23.99k ? If so whats ethicly wrong with cleaning the outside?


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## TXWolfie (Sep 20, 2011)

Cause if it is thru-out it will still come to the surface part of the gold that is touching the air.


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## mr-fixit (Sep 20, 2011)

So if I clean it it will re-tarnish in time?


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## jimdoc (Sep 20, 2011)

Mr-fixit,
Why are you creating these little 1 gram globules? 
Are you making them from a marked 24K bar?

Jim


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## TXWolfie (Sep 20, 2011)

Yes Jimdoc he is cutting 1g from a bar and melting it on stainless steel.




mr-fixit said:


> So if I clean it it will re-tarnish in time?



Yes as long as the gold was melted on anything metal it will always have that metal in the Au. The gold acts like a sponge and pulls it in to the mix. Like said before ya wanna get rid of it ya have to reprocess it and melt it on Fireclay, clay/graphite, silicon graphite crucibles. Any of the jeweler's melting dishes. Soft firebrick that has had an indentation scooped out with a spoon. NO metal!


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## goldsilverpro (Sep 20, 2011)

mr-fixit said:


> So if I clean it it will re-tarnish in time?



Face it. You screwed up the gold because of your lack of knowledge. Now you know better. Everybody goes through these screw-ups and that's one way we learn. The contamination is throughout the entire bead. The only thing that sulfuric will do is to remove the oxide (not tarnish) from the surface and make it look better. Cleaning only removes it from the surface. The next time you melt it, it will come up from the inside of the bead and will be right back on the surface. 

You can re-purify the gold by dissolving it in aqua regia and using the standard precipitation method, etc., as outlined in great detail on this forum. Or, you may be able to get it to an acceptable purity by simply melting it in a jeweler's melting dish with a torch and fluxing it with a pinch of borax and a prill or two of sodium nitrate - for a 1 gram bead, it won't take much - try not to overdo it. The sodium nitrate will oxidize the contaminating metals in the bead, bring these oxides to the surface, and they will be collected by the borax, which makes up the slag. When the surface of the molten bead is like a mirror, with no white scum floating on it, at all, it is pretty pure. If the contamination is severe, this is less likely to work.


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## Palladium (Sep 20, 2011)

What are you using these 1 gm bb's for? ebay?


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## mr-fixit (Sep 21, 2011)

Yes ignorance is bliss until you screw up  
Why do I want 1g bb's? I can see hyperinflation round the corner :!: 

Thank you one and all


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## mr-fixit (Sep 23, 2011)

Hello folks.
I've decided to go for melting method, its the least complicated.
Sodium Nitrate in prill form seems to be hard to find in the UK. Agricultural Sodium Nitrate in 25kg bags is available but I only need a small amount. I came across urea/carbamide, is this a suitable replacement?
Could anyone recommend a uk based supplier?

This is getting interesting


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## micronationcreation (Sep 23, 2011)

Surely the easiest way to make 1gram buttons from a bar is to dissolve the entire bar in AR and split the powder into 1gram batches.

I would worry about the losses cutting could cause.


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## Palladium (Sep 23, 2011)

micronationcreation said:


> I would worry about the losses cutting could cause.



Don't worry the Stainless will make up for that.


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## mr-fixit (Sep 23, 2011)

For your information there was no loss of weight caused by cutting and no gain in weight from the stainless. Scales 0.01.


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## micronationcreation (Sep 24, 2011)

Picture of my first attempt at 1 gram buttons a few weeks ago, they are a bit irregular/amateurish for my liking.
Food for thought though...


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## eeTHr (Sep 24, 2011)

The industry standard for gold bullion is three nines. Unless you started with Maple Leafs, or some other four nines gold, any contamination is going to result in less than three nines buttons. If you sell your grams as bullion, and someone checks it, you could be in for trouble.

Even if you start with four nines gold, if you have one thousandth contamination, you will have less than three nines in your grams.

They do look pretty cool, though, and would probably sell on ebay for over spot, I think.


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## butcher (Sep 24, 2011)

Nice but, for trading for bread, say they are 23k , 23.5K or higher, and a buyer he would have to test each one and would have no idea of the karat above 22K, now buyer tried with 22k acid test, they would show 22k and that would be the most they would trade for, by doing that with so many small beads you could lose a lot of gold in the trade, now try and trade them to the farmer who does not know how to test for gold, he may just tell you I will keep my cow, that could be brass for all I know, I would consider silver (coins or known silver content) like marked sterling, as barter for bread and keep the gold in larger bars. say I had a gold bar stamped 999.9 and got into a bind and needed some bread, which would you take in trade the beads you have or shavings from my assayed bar?

Same thing with marked sterling silver do not melt or cut it up, I would trade bread for pieces I witnessed cut off the candlestick that had the stampings before just some unknown white metals you had. Or take coins of known content or half's of coins.


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## micronationcreation (Sep 24, 2011)

> They do look pretty cool, though, and would probably sell on ebay for over spot, I think.



Thanks, i sold them on ebay last week and got average £37 gbp each,

I dont know the purity but the gold was put through AR twice and i use Harold's washing routine.


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## eeTHr (Sep 24, 2011)

micro---

Oops, I thought you were the Original Poster, with the contamination problem. Sorry.

Glad you got your price for them.


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## patnor1011 (Sep 26, 2011)

You can buy casting grain. Small balls of gold.


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## acpeacemaker (Sep 26, 2011)

Everytime I hear about this kind of stuff it always makes me think of drug dealing. (I can't help it, that's the way my mind works.) Going and buying a oz or lb. And then nickel and dimeing people to death. Now, its said that's where dealers go wrong is they end up using their own supply, therefore leaving them broke. So in comparison what happens to the person slingin' the gold?


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## patnor1011 (Sep 27, 2011)

Or another option is to buy gold sheet and cut in desired weight/shape...
I was offered this in one refinery - sheet with karat stamped on it. I once had ring made from my gold and got excess back in sheet stamped 585 (14k).


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## mr-fixit (Oct 4, 2011)

Hello folks, back for more help and info.
Melting dishes and Borax arrives this week. So the first thing to do is condition the melting dish with Borax, a thin even layer being preferable, just enough to seal the porous ceramic dish? Presuming this is correct, I have an idea. Make a borax paste and rub it into the dish. Dry it out on a radiator then warm up the dish with a torch before melting the borax directly.
Your comments and advice are welcome.


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## Geo (Oct 4, 2011)

try not to over complicate a process. if you have a hot plate it would be wise to use that. warm the melting dish as hot as the hot plate will get it, this will drive out any moisture and hopefully keep from cracking the dish. next heat the dish with your torch, keep the flame far enough back to heat the entire dish evenly. you will see small spots inside the dish glow brightly, this is tiny pieces of clay but are a good indicator of when to move the torch closer. during this phase there is no pattern to follow just be sure to heat the dish till it glows all the way through. have the borax ready, move the torch away and sprinkle borax liberaly around the edges. now apply the torch to the edge and work your way in pushing melted borax with the flame as you go. add borax as needed. when the entire inner surface looks wet and shiney remove the heat and either allow to cool or add gold and start your melt. if the dish cracks it is still useable but allow borax to cool and then reheat before melting gold.


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## Harold_V (Oct 5, 2011)

Key to successfully heating a new dish is to heat it very slowly, so entrapped moisture has an opportunity to escape before converting to steam. Once the dish is above the boiling point of water, you can pour the heat on quite quickly. 

For coating with borax, if you can obtain borax glass or anhydrous borax, it's a much more pleasant task. Neither of them puff up when heated, and are not easily blown about with a torch. 

Harold


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## mr-fixit (Oct 5, 2011)

Thanks for the advice folks :!: 
What if the decontamination, as described earlier, dosent work? And my 24k gold stays at 22k. Thats means Ive lost 8% of the value. 
Is is possible to add weight with silver and or copper by smelting with a melting dish and butane torch to make the gold 22k in weight, ie 91.6% gold?
By doing this I dont lose value.


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## Palladium (Oct 5, 2011)

Regardless of what you add you have already lost that gold. That gold is now part of the stainless steel that you melted it on. The only way to make it 24 karat is to process it again in acid. If you want your 8% back you will have to recover it from the stainless, re-refine your 22 karat and combine the lots to arrive at the original starting weight. Theoretically of course. 

You lost your value that is now gone and you want to replace it with something else, at somebody’s else’s expense so you don't lose money? I pity the sucker who get's taken. Am i reading that right? Please tell me that ain't your intentions. If that's the case i think i will have to refrain from giving any direction in this situation. If your here to learn that's great, but if it's the other........


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## mr-fixit (Oct 5, 2011)

My dearest Palladium, are you saying when I melted the 24k on the stainless there was mutual exchange, some of the stainless is in the gold and some of the gold is in the stainless? If so this I did not realise. I was told that molten gold acts like a magnet so I presumed there was no gold loss and only a slight contamination of the gold from the stainless. So are you saying that 8% of the gold is in the dish and 8% of the dish is in the gold? If you know what I mean.

I melted 1g of 24k in a stainless steel dish to form a globule to use as currency. After the globule cooled down it weighed 1g but is now 22k. I presumed the contamination of the gold must very slight because there is no increase in weight (scales 0.01), but enough to register the gold as 22k ie the golds purity is less than 999.

I am getting confused.

But hey what do I know about gold refining?

My aim is to rectify my mistake and not to rip-off anyone.


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## Geo (Oct 5, 2011)

actually it takes very little contamination to lower karat gold purity and there's no guaranty that the gold purity is that low. depending on the test used. if you would simply refine the gold im sure you would not lose any appreciable weight unless you lose it in another way such as leaving beads in the melting dish or blowing powder out of the dish with the torch. it takes a very sophisticated process to guaranty purity so either send the gold to be refined and sent back or take your chances and do it your self but theres no magic fix. i lost 20+ grams of gold to a simple mistake a couple of days ago and theres no magic solution to reclaim it. pull it together and refine your gold and make your buttons. it was a simple mistake and not one you are likely to repeat.


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## Harold_V (Oct 6, 2011)

mr-fixit said:


> are you saying when I melted the 24k on the stainless there was mutual exchange, some of the stainless is in the gold and some of the gold is in the stainless?


That's correct! You should know and understand that molten metals are strong solvents of other metals. You need not melt one in the other---it will dissolve, much the way sugar dissolves in water. So then, the chance that the gold you melted remains pure is not good. Not good at all. 

Wise people do not melt precious metals in metallic vessels of any description. 

Harold


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## mr-fixit (Oct 6, 2011)

Ive re-melted a button in a well Boraxed ceramic melting dish 4 times and it has turned out spotless, no tarnish or dicolouration just a shiny round button with a little dimple on top. What does this mean?


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## Palladium (Oct 6, 2011)

Good deal. How about a pic?


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## Harold_V (Oct 7, 2011)

mr-fixit said:


> Ive re-melted a button in a well Boraxed ceramic melting dish 4 times and it has turned out spotless, no tarnish or dicolouration just a shiny round button with a little dimple on top. What does this mean?


I'd assume it means the gold is pure. Melting and re-melting makes no difference so long as there are no base metals present to oxidize. Note that I'm assuming that the button you speak of is_* not *_submerged in borax when molten, but is exposed to atmosphere. If it is submerged, the shiny surface is meaningless. However, in that case, the color of the flux remaining can be an indicator of purity. It should remain free of color, or be colored nothing more than pink or (light) purple. 

The dimple you speak of tends to be a feature that is representative of pure gold. It's referenced as a *pipe*. It can be eliminated by controlled freezing, but those that know and understand gold look for the pipe to bolster the claim of pure gold. A frosty surface of a button is also a sign of less than pure gold. 

Harold


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## philddreamer (Oct 7, 2011)

If I may share a couple of pic's, one of a 24k button with a "pipe" & one 17.52k without; also notice the "frost".


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## mr-fixit (Oct 7, 2011)

Twas to good to be true. When I re-melt the buttons the tarnish re-appears. So the button have not magically cleansed themselves. When the button was molten I noticed dancing stuff on the surface, presumably contaminant, after about 30 seconds or so this stuff would make its way downwards and presumably in to the borax? I thought if repeated this process I could clean the button, apparently not. But what I did notice was if I put a low flame on a tarnished button the tarnish disappears, until its remelted. The pipe in the photo is not the same as my buttons, mine are more evenly rounded holes.


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