What causes platinum patina exactly?

[echelon6]

Is it: microscratches or chemical corrosion?

I''ve searched past threads to no avail to my specific question

I doubt it''s corrosion since Pt is so noble, and it''s not everyday you dip your hand in aqua regia...

But then if its microscratches, why would rebuffing and polishing remove micro-layers (as I read from a previous thread somewhere)? wouldn''t that just rearrange the Pt material without a net loss?

And another question: getting Platinum with patina repolished, does that cause a loss of platinum material?

 

[iheartscience]

I''m pretty sure it''s scratches. I don''t think platinum is easily corroded by chemicals. I don''t know if polishing removes layers of platinum or not.

 

[neatfreak]

It''s scratches and rebuffing/polishing DOES just redistribute the platinum. No metal is lost unlike with gold which is why platinum often lasts longer because scratches don''t make it lose any material.

 

[WorkingHardforSmallRewards]

I got the impression the original poster understood that patina was not the removal of metal, but rather the displacement of it. but, I think the question was more directed to exactly what types of contact cause for petina, and why does platinum get "pushed around" so easily. Obviously gold does not scratch at the same rate that platinum patinas or it would be gone in a couple of years. Which isn''t the case, so clearly while it might take a major impact or very rough surface and some hard force being applied to scratch gold, it must require much more gentle and less forceful impact to cause the platinum to displace. so what type of forces and contact, exactly, cause the micro-scratches of patina?

 

[echelon6]

WHFSR: Actually I was just asking, quite literally, what I posted :p but I''d also like to know the answer to your question too

I believe doing things like holding coins, or dirt on hands, or doing the dishes etc can all cause microscratches on Pt.

Neatfreak: I dont think you''re correct, as a few past posts have said that repolishing does forcefully remove some of the material.

If this is true, it makes me reluctant to do a repolish...

 

[neatfreak]

Date: 8/5/2007 7:13:51 PM
Author: echelon6
WHFSR: Actually I was just asking, quite literally, what I posted :p but I'd also like to know the answer to your question too

I believe doing things like holding coins, or dirt on hands, or doing the dishes etc can all cause microscratches on Pt.


Neatfreak: I dont think you're correct, as a few past posts have said that repolishing does forcefully remove some of the material.


If this is true, it makes me reluctant to do a repolish...

I'm pretty sure that one of the reasons people get platinum is that polishing/buffing does not remove the material, it only moves it around. I will try and find out more, but I know I have been told this before many times.


ETA: The Platinum Guild of America has an article that addresses this topic. They do say that it will lose a tiny bit of material over time, but it isn't a significant amount. As I said before, when platinum scratches, it creates a "ridge" of metal around it, and when polished, most of the metal is just smoothed out and NOT lost as it would be with gold.

 

[echelon6]

I think you''re mixing up scratching from normal wear (no loss of material) vs repolishing (levels out all the ridges by forcefully removing material) perhaps?

 

[neatfreak]

Date: 8/5/2007 7:30:41 PM
Author: echelon6
I think you''re mixing up scratching from normal wear (no loss of material) vs repolishing (levels out all the ridges by forcefully removing material) perhaps?

I''m just relaying what I have been reading, which I guess isn''t the same thing as what you''ve been reading! My jeweler told me that when platinum is polished it just smoothes the ridges out and you lose very little metal, unlike with gold. It seemed to me that it basically reversed the scratching process if that makes sense, but I could be understanding it incorrectly.

Maybe one of the experts will chime in here on this one?

 

[iheartscience]

I''m with neatfreak on this one. I''m pretty sure I''ve read the same thing several times. Repolishing moves the ridges back into the scratch, it doesn''t shave an entire layer of platinum off. It wouldn''t make much sense to use platinum if everytime you got it polished you removed a whole layer of platinum.

 

[strmrdr]

It is caused by bling cat spirits.
They have sharp claws and haunt platinum rings at night.

 

[shel]

My appraiser told me that polishing does remove platinum.

 

[strmrdr]

Date: 8/5/2007 7:52:17 PM
Author: thing2of2
I''m with neatfreak on this one. I''m pretty sure I''ve read the same thing several times. Repolishing moves the ridges back into the scratch, it doesn''t shave an entire layer of platinum off. It wouldn''t make much sense to use platinum if everytime you got it polished you removed a whole layer of platinum.

yep
you lose a very small amount but its not as much as with Gold or other metal.

 

[strmrdr]

Date: 8/5/2007 8:06:32 PM
Author: shel
My appraiser told me that polishing does remove platinum.

technicaly true but done right it mostly just moves it around.

 

[JohnQuixote]

Date: 8/5/2007 7:19:00 PM
Author: neatfreak

ETA: The Platinum Guild of America has an article that addresses this topic. They do say that it will lose a tiny bit of material over time, but it isn't a significant amount. As I said before, when platinum scratches, it creates a 'ridge' of metal around it, and when polished, most of the metal is just smoothed out and NOT lost as it would be with gold.

The PG is right.Platinum’s density makes this material loss insignificant.

If you want to make 'insignificant' into 'non-existent' you can have the surfaces burnished beforehand.This is where a polished steel tool is rubbed all over the areas with patina, forcing the high points back into the low points in order to make the surface smooth again. It’s then polished with no loss of material.

The best way to maintain a high polish is to avoid bumping the ring into anything. When all is said and done your individual habits factor most in your ring's appearance over time (tho it can’t hurt to have a paranormal expert perform a bling cat exorcism if you’re really worried).

 

[neatfreak]

Thanks John for the clarification. I was pretty sure that I was right on this one, glad to hear that I haven''t been telling people the wrong thing!!

 

[angeline]

Date: 8/5/2007 7:54:22 PM
Author: strmrdr
It is caused by bling cat spirits.

They have sharp claws and haunt platinum rings at night.

 

[shel]

I wonder what the lollipop guild has to say...

 

[echelon6]

So what I gather so far is:

1) Patina is caused by microscratches
2) Repolishing does in fact remove material

How much is a burnish / repolish job going to cost? Are there any inherent dangers / harms from burnishing? e.g. can they bend your ring if too much pressure is applied?

 

[iheartscience]

I''m sure the price depends completely on your jeweler.