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Recieving poor quality from mint V's Cleaning?


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Not sure why an 'NGC cleaned coin' is not the same as a 'cleaned coin'.
The only difference is the method used and that maybe if done properly no-one can tell but the coin is still cleaned.

Cleaning a rare sovereign would be a different project to cleaning a grubby 1996 silver Maple.
Cleaning will involve the removal of grime and oxidations so will involve baths in solvents, acids or whatever liquid dissolves these contaminants.
Either applying cleaning solution under pressure and / or ultrasonic to remove stubborn contaminants.
Any rubbing of the surface will introduce fine scratches as tiny particulates will gouge the soft metal.

If the surface is degraded then on some coins it will be possible to polish.
I doubt polishing a matt finished surface is possible because the surface is intentionally disturbed ( like sand blasted ) and polishing would flatten this leaving behind a more shiny look.
Some coins have a frosted background field and a mirror finish cameo to enhance contrast.
The mirror parts can be polished to remove scratches and blemishes but not the background.

Polishing can fall into two main categories -
- extremely fine abrasive removal of top layer with a filler left behind to enhance the reflectivity i.e. shininess which cutlery, door handles, trophies etc all desire.
- as above with no residue i.e. clean

As far as I can tell, a coin like a Maple can be re-polished to perfection using jeweller's rouge leaving behind no scratches etc if done properly.
If the coin has milk spots or fine scratches these can be "polished out " by using a series of polishing compounds that are a bit more abrasive ending with red jeweller's rouge.
I think, but not entirely sure, the majority of commercial metal polishes ( e.g. for cars ) although work well do leave behind an enhancer and that's what the "experts" can detect and on large items feels a bit slippy so a kind of wax maybe ?

 

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15 hours ago, manolitolondres said:

Is ultrasound bath good enough to clean gold or silver coins? I have one in my lab, might try on one old sovereign

If you're going to try it just make sure that the sovereign hasn't any numi value or you could wipe all that value away in one clean sweep!

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15 hours ago, manolitolondres said:

Is ultrasound bath good enough to clean gold or silver coins? I have one in my lab, might try on one old sovereign

I hear you have to be careful with the coin touching the tank surface can cause scratches. I don't actually know that, just heard it somewhere 🤷‍♂️

 

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