Short answer: Silver Overlay refers
to a heavy pure silver electroplate
on the surface of a piece of jewelry.
Silver Overlay means a heavy electro-plate of pure silver
one that will NOT wear off in a very long time even with use.
At a well-equipped silver-electroplating shop, the operator employs an external source of DC current (a rectifier) so the plating proceeds regardless of the material of construction of the item being plated and continues long past the point where the base metal is merely covered, on until a very significant thickness of silver is deposited (measured in thousandths of an inch). The plating shop may also employ a number of processes on the piece of jewelry covering over any solder, filling any pits with copper, leveling the surface with a pre-plating, and buffing to a bright luster, all before silver plating. These technical details are coordinated between the artisan and the silver electroplating shop.
Do-It-Yourself Silver Overlay Upgrade and Repair
A piece of jewelry which was originally silver overlayed, and you wish to build up a thin spot, you can apply additional silver to it at home, with no electricity required, from a simple wipe-on or dip process sold under trade names by commercial vendors. Some products you will you the articles into the solution, with other products you wipe the solution onto the article.
What happens in such repair plating processes is that the silver in the solution and the exposed brass or copper alloy, for example, German Silver alloy, of the jewelry piece in question form a battery wherever the silver has worn through. The silver is more "noble" than the copper; this provides a voltage that simultaneously dissolves some exposed copper into solution while plating out the silver that was in solution.
There is a limitation of this Silver Overlay repair process. It is that once the copper or brass alloy has a thin silver plating all over it, there is no more exposed copper or brass so the "battery" is dead, and no more silver will deposit. Therefore, you can only get a thin coating of silver -- millionths of an inch -- so the longevity and durability of the repair overlay is limited.
All of the wipe-on or dip-in brands work on exactly the same principal, which is not to say that all the brands are identical; some feel that some brands are better than others, and it may have to do with the silver concentration, the ease of use, the polishing agents in the mix, etc.
Several brands of this product are usually available on E-bay, hopefully the ever-changing E-bay ads provided here prove helpful (if the ad shows a lusty babe or a get-rich-quick scheme, sorry, interent marketers sometimes substitute their most profitable ads, when, for some reason, no silver solution is available on a given day)
Sourcing of resilvering solution
1. Jax Silver Plating Solution: avail. from this link at Amazon.
2. Medallion Liquid Silver Plating Lotion: avail. from this link at Amazon (but often out of stock).
3. Quickshine Pure Plating Spray: avail. from this link on ebay.
Caution: Quickshine Silver Bath is a different product and appears to be for tarnish removal/polishing, not for resilvering.
4. Butler's Secret Instant Silver Plate: avail from this link on ebay.
5. Silver Plater --> [United Kingdom] proidee.co.uk/shop.
6. Silver Secret --> silversecret.com presently not able to find a source.
7. Sheffco Silver Solution --> www.kernowcraft.com [United Kingdom]
What is electroplating?
Electroplating deposits a metallic coating by placing a negative charge on an object and exposing it to a solution containing a metal salt. The positively charged metal ions in the salt solution are attracted to the object and reduced to metallic form upon it.
How does it work?
Look at the diagram below: We have a metallic object we want to plate with a metal. First we fill a cell with a solution of a salt of the metal to be plated. Most of the time the salt (nickel chloride in our example) is simply dissolved in water and a little acid.
The NiCl2 salt ionizes in water into Ni++ ions and two parts of Cl- ions.
A wire is attached to the object, and the other end of the wire is attached to the negative pole of a battery (with the blue wire in this picture) and the object is immersed in the cell. A rod made of nickel is connected to the positive pole of the battery with the red wire and immersed in the cell.
Because the object to be plated is negatively charged (by being connected to the negative pole of the battery), it attracts the positively charged Ni++ ions. These Ni++ ions reach the object, and electrons flow from the object to the Ni++ ions. For each ion of Ni++, 2 electrons are required to neutralize its positive charge and 'reduce' it to a metallic atom of Ni0. Thus the amount of metal that electroplates is directly proportional to the number of electrons that the battery provides.
For an affordable introductory education in electroplating, we recommend getting a copy of the Metal Finishing Guidebook. Some libraries may have it but, if not, because it is an annual book that is included with a subscription to Metal Finishing magazine, old copies are readily available and inexpensive from used book dealers.
Electroplating Engineering Handbook, Lawrence Durney