Spots on Premium Silver, How come?

Hi,

I recently ordered an item in Premium silver, and it came out with some spots (1-3mm) on it that were darker than the surrounding silver. It does not come off, not even with cleaning wipes, so it really seems to be in the material itself.

Check the image.



Does anyone (staff at Shapeways?) have an explanation for this?

Thanks,

Ralph

Perhaps some polishing compound? I'll investigate. Have you contacted service (reprint or not, it's good to give them feedback positive and negative).

Do you have any larger photos you can share? If you don't want to make them public, send them to service and they'll keep them internal. If you want, you can email them to me as well so I can help investigate.

What you see on your part is referred to as firescale. Which is an oxide of copper which forms on the surfaces of sterling silver during the casting process. Usually this is just on top of the surface of a casting but sometimes it can form slightly below (microns) the surface. Firescale needs to be removed either chemically (before polishing) or mechanically during the polishing procedures. Sometimes a polishing technician might miss a spot or two which I think is what has happened here. :blush:

-G

Hi, I've also received a pair of cufflinks made in raw bronze and with such an issue. See my post here https://www.shapeways.com/forum/index.php?t=msg&goto=941 07&&srch=bronze+stain#msg_94107

Is this an oxide of copper as well ? on top of the surface and can be polished off ?

Like Numarul7 said in the other thread: