Friday, December 18, 2015

Fine silver overlay construction

The differences between early fine silver (.999) overlays and later overlays in sterling silver (.925) go well beyond metal content. Sterling silver overlays were made from sheet stock, rolled into tubes. Fine silver overlays were made by electrodeposition, and instead of being pushed onto a hard rubber pen, they were generally plated in place. On the barrel, a recess was cut so that when the silver was deposited, the surface of the silver would be level with that of the adjacent hard rubber. Cuts were made into the surface of the hard rubber where the silver was to go; once the silver was plated into and over these cuts, the overlay would be locked in place -- which is why you never see a fine silver overlay that has rotated or shifted, whereas this is common with sterling silver overlays, even where they have been crimped in place.

This construction is clearly visible in these photos of a Waterman barrel which formerly carried a fine silver filigree overlay.

Fine silver was also used for some of Waterman's early non-filigree overlays, such as this acid-etched half-overlay shown below. The same method of construction was used, and the photo clearly shows how the surface of the silver is level with that of the hard rubber. In this case the metal is not marked as being fine silver, but it is apparent that is what it must be.

There are other construction details that can also indicate electrodeposited fine silver, even when the metal is marked "STERLING", as is often the case. This is especially common in brands other than Waterman, perhaps due to sterling being by far more recognized by the general public, then and now.

The blobby splash of silver on the rim of the cap of this Waterman is a giveaway. Surface lumps simply don't occur on sterling silver flat sheet stock (or tube stock, though this was not the norm until much later). Another giveaway on filigree pens is scoring of the hard rubber at the perimeter of the cutouts, where the workman cut a little too deeply through the soft silver. This is generally not found on overlays made from sterling sheet stock, where the cutting must have been done with the overlay mounted on a mandrel. This clearly wasn't an option when fine silver was plated directly onto the hard rubber cap.

Scoring of this sort isn't always found on fine silver filigrees, however, especially on pens where the silver layer is very thin. As noted in a 1909 article (The Metal Industry, vol. 7, no. 7 (July 1909), pp. 241-242), selective deposition was another method used, as was removal of material by either reverse plating or dissolving with acid. Although I seem to have misplaced the photo, I own a Waterman "Chased" 222 with a "STERLING" mark in relief, which could only have been done by one of these three techniques, strongly suggesting that the entire overlay is actually electrodeposited fine silver. And while the 1909 article only discusses deposition directly onto caps and barrels, there is an illustration of what appears to be a Waterman Puritan/Patch -- confirming that complex relief work was being done by deposition and not just flat surfaces.

How might this have been done? I would posit that instead of plating directly onto hard rubber, a layer of pitch would have been applied, and the relief design impressed into the pitch. The impressions would be retouched by hand as necessary, then the pitch given a conductive coating and plated. The design would be somewhat softened, in essence being molded from the back, but could be sharpened by judicious use of hand chasing. The alternative would be to plate inside a multipart female mold, which would also require some hand finishing to clean away seam lines.

Much surely remains to be discovered about the making of overlays. As a final snippet, I will add the following, which appears in the previous issue of the same journal (The Metal Industry, vol. 7, no. 6 (June 1909), p. 234):
Geo. T. Byers, 69 John street, New York, manufacturer of gold and silver chased work, has recently put in a plant for silver deposit work on fountain pens, etc.
ADDENDUM: The image below illustrates how the cuts made into the hard rubber before plating could leave visible traces on the electrodeposited silver surface. These "nicks" are commonly found on thinner overlays, and are usually assumed to be the result of wear and usage rather than artifacts of original manufacturing methods.

1 comment:

David said...

An added note, originally in response to a query on Facebook:
Electrodeposition of alloys isn't as easy as depositing a single pure metal. This is definitely the case with silver, and was all the more so 100 years ago. The use of fine silver was necessitated by manufacture by electroforming -- it would not have been chosen over sterling otherwise. Conversely, if you were making a silver overlay from rolled sheet stock, there would be no reason to use anything other than sterling.