# gold jewelry finishing with aqua regia



## diverwild (Mar 31, 2016)

Hi 

I make gold cast rings and it is very difficult to get mirror finish inside the ring with normal polishing 
so I tried to put a ring in aqua regia and it started to remove some roughness , I removed the ring washed it, and I noticed that there is grey layer that could not be removed
even after annealing it and putting it in Hydrochloric acid this is my experiment and I want to know

1 what caused that grey layer and how to remove it

2 is there any chemical better than aqua regia to be used for gold finishing 

your help will be much appreciated Thank you


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## upcyclist (Mar 31, 2016)

diverwild said:


> 2 is there any chemical better than aqua regia to be used for gold finishing


Personally, I would never use chemical finishing on jewelry. I would suggest non-chemical (mechanical) means (links from Rio Grande for illustrative purposes only):

1. Use a flex-shaft (like a Foredom) or dremel, with the associated mandrels/buffs/wheels. There are also cylindrical wheels made specifically for polishing inside rings. The 3M radial bristle discs are also groovy.
2. Get an inside-ring mandrel for your buffer/lathe
3. Tumble them, either with polishing media or burnish with stainless steel


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## nickvc (Mar 31, 2016)

The normal way to tidy up castings is to strip them in cyanide to remove the fire stain first then to use a buff stick and remove the rough areas, put them through a barrel with stainless shot to give a brightening to the castings and then hand polish on the mops to get the required high polish.
There are set ups now that avoid a lot of the work using different media to save on the manual work but they never really seemed that good to me, you can also use cyanide bombing to remove the fire stain but that needs a proper cabinet as its cyanide and peroxide mixed if I remember correctly.
Bottom line is of you are making quality pieces stick to the traditional methods they may take a little longer but the end result cannot be beaten by machinery or chemicals.


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## g_axelsson (Mar 31, 2016)

Sounds like the alloy contained some silver that formed silver chloride on the surface.

Göran


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## lanfear (Mar 31, 2016)

And if that is the case, you can remove the grey with hot amonia. But if your ring will look nice after I dont know.

Jon


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## upcyclist (Mar 31, 2016)

lanfear said:


> And if that is the case, you can remove the grey with hot amonia. But if your ring will look nice after I dont know.


That's the thing--acids are generally used for etching (in my shop, at least), not for putting a shiny coat on something. I produce everything by hand, so I'm not familiar with how a production shop might do it (e.g., cyanide bombing). As Nick said, traditional methods produce the best polish, which is why mass-produced stuff never looks as nice. 

Oh, when I said mechanical, I meant friction-based processes (as opposed to chemical), not necessarily electrically-powered stuff. Though if a Foredom moves rouge quicker than I can with pure elbow grease, I'm all about the Foredom, haha. I do tend to favor a Foredom over a big polishing buff on a lathe.


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## publius (Apr 1, 2016)

I can't help with the gray stain but, if you would search the web for "electropolishing" I think you will find what you need. Buehler is a manufacturer of such equipment.


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## diverwild (Apr 2, 2016)

lanfear I will try that amonia thank you


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## diverwild (Apr 2, 2016)

publius said:


> I can't help with the gray stain but, if you would search the web for "electropolishing" I think you will find what you need. Buehler is a manufacturer of such equipment.



electropolishing! sounds interesting

I will have a look thanx


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## Schraer3 (Sep 26, 2017)

Hi diverwild!

Dont know if my answer is still usefull, as you asked quite a time ago.....

Your problem of not being able to polish the cast rings from the inside comes from the cristal structure of your cast. Means that the cristals forming the metal are very big (its totally normal on casted metal). 
So when you try to polish you get stripes and pickles cause the size of the cristals prevent a better polish.

What you can do to get a better look of them is to surficialy break the cristals into smaler ones (its what smithing/compacting does with metal, it breaks the huge cristals into smaller onces and makes the metal more malleable, break resistant and able to get better/more even surfaces.

You can buy in jewelry tool stores metal wheels which perform as a microhammer. This would do enough compacting to get a nice mirror polish. 
They look like this: https://www.artsupport.ch/de/shop?aid=6904 and are used with a mikromotor.


Hope it was of any use,

Greetings! :wink:


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## g_axelsson (Sep 26, 2017)

I've seen homemade hammer-wheels, just an axle through a copper coin and then filed a couple of grooves (6-10) around the edge. Works just as good as the bought ones. Copper or bronze so it doesn't scratch the surface.

Göran


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## autumnwillow (Jan 21, 2018)

How many rings?


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## Suresh bhatti (Mar 21, 2018)

Aquaregia solution is not for ornament polishing or finishing. why did you put your ring in aquaregia ?
You have to analing your ring and put in diluted sulphuric acid with water
Then buff it with black laster for finishing it then buff it with red laster. Then wash it with detergent shop to remove buff particle. And last heat pure sulphuric acid in beaker and shake it for 10 to 15 seconds then pull out your ornament, get rather cold and dip in water.
Dry it in wooden powder.


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