Why does silver plate not oxidize well?

[Luann Udell]

I saw the latest post about plated wires & such.  Not wanting to hijack a thread, but the topic reminded me of something I've wondered about. 

When I oxidize sterling silver stuff (clasps, ear wires, etc.), I sometimes throw in a few silver-plated items, something like these:  http://shop.rings-things.com/cart/pc/viewPrd.asp?idcategory=0&idproduct=19217

It seems that the sterling silver stuff oxidizes pretty quickly, but the silver plate stuff hardly oxidizes at all. 

I actually tried this awhile ago with some silver plated wire I bought at a R&T show, and the stuff just wouldn't oxidize.

Are things like that lacquered in addition to being plated?

[Russ Nobbs]

Good question, Luann.

Often, but not always, silver plated and copper plated things have an anti tarnish lacquer finish.  There are some other anti tarnish techniques that are not a lacquer. I forget those details right now. Often sterling items have anti tarnish finishes, also.

Using Liver of Sulfur ( LOS ) the lacquer often comes right off and looks like a thin flake that turns black as it flakes off.

Using other antiquing solutions you may need to soak the findings or wipe the wire with acetone( fingernail polish) to remove the anti tarnish lacquer.

We are trying to consistently find out and list if an item has an anti tarnish finish.
We forget to ask or the vendor does not understand or, in some cases, the vendor sends it out for plating and does not really know what finish was used.
I think TierraCast® always uses an anti tarnish finish of some sort over their silver plate and antique silver plate. I'll try to remember to ask after the dust (mud?) from Tucson settles down.