Technical Question About Silver Overlay

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Technical Question About Silver Overlay

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Author	Topic: Technical Question About Silver Overlay
Dale Posts: 2132 Registered: Nov 2002	posted 08-30-2004 09:29 PM [01-1700] Had something come up and find I do not really have an understanding of this subject. The item in question is a piece of Lennox with a silver overlay. It is a vase, Art Deco, probably early 1930's. The china is glazed, the silver is in the shape of triple broad wires accenting the form. Now what I wonder is this: does the silver go on before or after the piece is fired? I feel that before would make sense as the heat of the kiln would not be sufficient to melt the wire but enough to let the glaze under the silver mold the wire to the form. Really don't know for sure. I can see a good reason for doing it afterwords, but that seems unreasonably labor intensive. Does anyone know the standard practice on this technique? IP: Logged
dragonflywink Posts: 993 Registered: Dec 2002	posted 08-30-2004 11:51 PM My Mom has collected both glass and ceramic silver overlay or deposit pieces for years, so I'm curious to hear a good answer. My understanding is that the pattern is etched on the glass or glaze and the silver is added through some sort of chemical reaction. Don't know if that's right or not. I do know that there are a few (very few) companies that still do it, and Lenox has put out some very pricey collector-type pieces in the last few years. As for firing the piece with the silver, have to go back many years to when I worked with kilns, and seems to me that most glazes fire at around the 2000 degree point (not really sure, we used cone #s rather than temp.). Think the melting point of silver is a not quite that high? I'm sure that our forum silversmiths will let us know! Regardless, even if the metal didn't melt, I'd think the glaze would maintain an even level with the silver (or even slip over the edges a bit) rather than the silver being slightly raised, as it is on these pieces. Adding a picture of the one piece I own, a gift from Mom. It's Lenox, from the 1920s-30s, is deep cobalt blue, and has nice engraved details. She bought it as a tea jar, I've never seen another like it, anybody want to second that opinion? Measures approx. 5" tall, 3-3/8" dia. at the widest point, and the opening is 2-1/8" in diameter. Cheryl IP: Logged
Dale Posts: 2132 Registered: Nov 2002	posted 08-31-2004 12:37 AM Thanks Dragonflywink. This is a puzzlement. I understand, hopefully with some degree of correctness, that deposit is a variation of electroplating. Which means that the silver is deposited on the glass. But the overlay continues to confuse me. I have had pieces where clearly the glass fitted into a silver frame. Yet there are others where it seems the silver and ceramic were made together. I hope someone will explain this, but I suspect that the technique involved is a number of different ones. IP: Logged
dragonflywink Posts: 993 Registered: Dec 2002	posted 08-31-2004 01:17 AM There is definitely a lot of confusion as to what defines silver overlay and silver deposit. Not to mention the silver resist items I've seen being sold as overlay. Hope someone can shed some light on this. Can't seem to find my resources on this right now, but it seems like the 1930s-40s Cambridge Glass pieces with silver were in their catalog as "deposit". On the other hand, I believe that Lenox (did I save any of those recent ads?!?) referred to the new pieces as overlay. Mom has some pieces where the silver is definitely separate from the glass, but no ceramic pieces made that way. Cheryl IP: Logged
jorgy Posts: 11 Registered: Aug 2004	posted 08-31-2004 01:49 AM In "cloisone'" metal wires are used to seperate the enamal and its fired at one time usually. IP: Logged
mefecit Posts: 7 Registered: Mar 2004	posted 08-31-2004 09:36 PM Hello: Metalsmith here with some info. "Deposited Siler" can be done is at least three ways: Chemical deposit, this is how mirrors are "silvered", Ammonical silver nitrate will precipitate a pure silver film on glass if the right precipitants are added to the solution. If it is stopped out with wax, a pattern can be deposited. This is a very thin film and was mostly used on glass. Silver leaf fired into or under low firing temp clear gaze or enamel, not much different from fired enamel on silver, just the silver applied to the enamel rather than the other way round. This is thin also, because of cracking do to different rates of expansion. Below 1500 deg. F. Electro deposited "electro formed", Basically plating on anything that will not conduct electricity. A wax or paint with graphite or metal powder in it to make it conduct is applied, then a heavy plating is built up over that. The neat trick is, it is possible to melt out the wax after a heavy enough layer is formed, then resume plating. Silver will deposit on both sides of the newly formed metal, and if done long enough,will build up all the way back to the surface of the object. Now "overlay" is not so well defined. It can be a carefully fitted silver "setting" for an object. Very much like setting stones. Silver will let you do an amazing amount of "pulling and pushing" to snug things up. Fine silver is even more pliable, that is why some early fitted silver over glass is pure .999 fine. Think of this as pulling a knitted sock on. If your piece has signs of being made from sheet and cut out or wires soldered, it was made this way. This is far from complete, but I am a poor slow typer and would take all night to write up a complete description. Bye Mefecit IP: Logged
bilgi Posts: 20 Registered: Aug 2004	posted 09-04-2004 01:37 AM Hi, Just for additional info: Enamel over filigree, a variety of cloisonne enamel, was very popular in Russia. A floral or geometrical ornament of twisted wire is soldered onto the metal base. Each of the received cells is filled with enamel of different colors. After the firing the enamel lies somewhat lower than the filigree ornament; to avoid the damage of the pattern shaped by filigree wire, the enamel is not polished. The absence of polishing and the level of enamel being lower than the partition edges are the characteristic features of enamel over filigree that make it distinct from the standard cloisonne technique. For the enamel with filigree technique colored transparent and non-transparent enamels as well as colorless transparent enamel are used. Among metals, gold and silver are preferred, articles as well. IP: Logged

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