Tungsten Carbide Wedding Ring is Dirty 2

[cculp]

So,

Here's a less-than-usual question for you all. I got married a couple years ago. Upon visiting the local jeweler shop, owned by a friend of the family, I found that he was offering Tungsten Carbide Wedding Bands.

Wow, that sounded really cool, I thought, being a mechanical engineer. I could be wearing one of the hardest known materials around my finger, and it's even half the price of gold. So I went for it.

Well, besides the drawback of it being very heavy, it also has one problem, and that is that it tarnished within a month or two. It at least looks like tarnish, although my understanding is that that's impossible, as tungsten carbide shouldn't be able to tarnish, as it is not really a metal, it is a ceramic.

So, regardless of whether it is just tungsten, or tungsten carbide, it still looks rather trashy. I walked down to the machine shop this morning, and discussed it with the shop foreman. We tried a buffing wheel, which made it shiny, but still looks "dirty". We tried scotch-brite, which lightened some of the dark & dirtyness, but made it dull. There are still patches of dark & lightness, so it is not a clean look. We then tried what he called jeweler's rouge (Fe2O3), although it was a white paste, I thought it was always red.

Anyway, the ring is still not shiny, and still splotchy. Does anyone have any ideas for a nice clean finish? The ring was originally shiny, although I would be comfortable with a matte finish. Taking Aluminum Oxide to it is too abrasive, and would leave too rough of a finish.

The ring shape is a flat surface, with two chamfered edges, then a rounded interior. It looks something like this link, although it has a larger flat surface:

http://www.tungstenpride.com/ProductDetails.aspx?productID=21

Let me know what you all think, I am very interested.

Charles Culp
Design Engineer - Solidworks User

 

[EdStainless]

I think that you should have left well enough alone. After all it had reached a stable patina. My Pt ring isn't bright any more. Now it will look the same forever.
Part of your discoloration could be the binder (Ni or Co) that holds the WC together. These are not solid WC.

If you really want to refinsh it you need a buffing wheel and some diamond paste. Nothing that you have tried so far is hard enough to actually polish it.
Take it down to the metallography lab and ask for some help.

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Plymouth Tube

 

[unclesyd]

You probably have a Co binder in lieu of Ni binder. If Co the it reacts with the skin oil and oxidizes to an almost impossible layer to remove chemically or mechanically. The above advice about diamond polishing is well taken. Be careful and don't get carried away. If worst come to worst you might try a little diamond paste with the product below.

Key point is don't put it in an ultrasonic bath

I have had some success with Brasso metal polish. The more expensive one, I forget what it's called. I would use a Dremel Tool with the cloth polishing wheel.
Most all hardware stores carry this product.

I've also had some success with both Semichrome and Blue Away on some pieces.

Here is the distributor but you can get it from several sources. A good place to check locally is a welding supply.

http://www.competitionchemicals.com/

 

[swall]

Simichrome, perhaps, unclesyd?

 

[unclesyd]

swall,

Correct!

 

[cculp]

Thanks for the responses. It sounds like that is the way to go.

As per "finding it's natual patina" I would normally agree...

Except that it is not an even finish. I would be quite happy with a finish that is more dull, I'm just not happy with how blotchy it looked. There were definite areas of darker and lighter colors; some more shiny others bland. As the topic title says, it looks "dirty".

So I guess if I want to return it back to its original shine it is diamond paste, I might give that a try. Of course it will just get darker again, I just need control it so it is more even.

Charles Culp
Design Engineer - Solidworks User