VintageWatchstraps Logo

Vintage Watchstraps

Straps for Vintage Fixed Wire Lug Trench Watches or Officer's Wristwatches



Non-precious Case Metals

Copyright © David Boettcher 2005 - 2024 all rights reserved.

This page is about non-precious metals, that is not gold, silver or platinum, used for making watch cases, apart from Stainless Steel, for which there is a separate page.

Black Oxidised Steel Watch Cases

Watch cases were sometimes made from steel, This was cheaper than gold or silver, but prone to marking and rusting. To make the case more attractive and give it some protection against rusting it was hot chemically treated . The process turned the steel black and the cases were described in Swiss/French as "acier oxide", or oxidized steel. The oxidised finish was attractive and reasonably satisfactory in everyday use, but it was not very successful in preventing rust in damp conditions. When these cases are seen today the black surface layer has often worn thin or been removed by polishing, showing the silvery grey of the underlying steel.

Jean Finger advert 1894
Jean Finger advert 1894

Black oxidizing, or caustic black as the process is sometimes called, involves immersing steel parts in a caustic soda (sodium hydroxide [NaOH]) salt bath at about 140 degrees Centigrade (290 degrees Fahrenheit). The reaction between the iron in the steel and the hot oxide bath produces magnetite (Fe3O4), which forms an attractive and moderately corrosion resistant dark black finish on the surface. The parts are usually oiled or waxed after treatment to improve corrosion protection. Because of the temperature and the caustic materials involved, this is a dangerous process.

Some idea of the specialised nature of the process may be gained from the advertisement here by Jean Finger, a case maker of Longeau who later patented the hermetic watch case, or case within a case. This advertisement is from April 1894 and at the bottom says "Oxidages soignés de boites acier n'étant pas de ma fabrication", i.e. that the company will carry out oxide treatment on steel watch cases that are not of their own manufacture; they will treat watch cases for manufacturers who don't have the capability to do it themselves.

The second advertisement appeared in the 1901 Goldsmiths Company Watch and Clock Catalogue for a military pocket watch, The Company's Service Watch. It was described as “The most reliable timekeeper in the World for Gentlemen going on Active Service or for rough wear.” The UNSOLICITED TESTIMONIAL at the bottom of the advert, dated June 7th 1900, states Please put enclosed Watch in a plain Silver Case. The metal has, as you can see, rusted considerably, but I am not surprised, as I wore it continually in South Africa on my wrist for 3½ months. It kept most excellent time, and never failed me. Faithfully yours, Capt. North Staffs. Regt.

1901 Goldsmiths Advert
1901 Goldsmiths Advert - Click to enlarge

The Captain's watch was the version cased in an oxidised steel case shown in the middle picture. This made the watch, at two pounds ten shillings, considerably cheaper than one with a silver case, which the advert shows was priced at three pounds ten shillings, a considerable increase of one pound; 40% more. The 18 carat gold case was considerably more at twelve pounds, nearly five times as much as the one in the steel case. Which raises an interesting point; the same watch movement could be housed in either a steel, silver or gold case at the customers choice. As the mechanism was the same in each case, its cost must have been the same, and must have been part of the cost of the cheapest watch, the steel one, at two pounds ten shillings. The difference in cost of nearly ten pounds between a steel and 18 carat gold case watch was therefore entirely due to the extra cost of the gold case. A rough estimate might put the cost of the watch movement at two pounds and the steel case at 10 shillings, giving the price of the steel watch at two pounds ten shillings. Which would make the gold case, at ten pounds, twenty times as expensive as the steel case, and five times as expensive as the watch movement itself.

You will notice that the Captain says I wore it continually in South Africa on my wrist for 3½ months. This was during the Boer War in South Africa, and he had been wearing his watch in a leather wristlet, which you can read more about on my page The Evolution of the Wristwatch: Wristlets. During the same war a Borgel watch in an oxidised steel case spent several days in the Modder river.

A particularly attractive use of black oxide finish in combination with gold was used by François Borgel to create a case for an IWC pocket watch with a stunning dragon design which can be seen by following this link: Borgel black oxidised dragon case.

Gunmetal?

The same process is used by gunsmiths to produce an attractive cosmetic appearance and measure of corrosion resistance to firearms; because of this the finish is sometimes called "gunmetal". This is unfortunate because gunmetal is really a copper alloy similar to bronze that was used to make cannon before large steel forgings were possible.

When used in regards to watch cases, "gunmetal" doesn't refer to the type of metal used, which is steel, but only to the black, or sometimes dark blue, surface finish. In 2012 the Swiss watchmaker F.P. Journe presented in New York City an exhibition entitled "Steel time: The largest historic collection of gunmetal watches of the mid 19th century". I thought at the time, and I still think, that this is a very unfortunate use of the word gunmetal; collectors need to be aware of this usage but I hope they will avoid propagating it, or at least qualify it as "gunmetal finish".

Bluing

A similar process using a solution of potassium nitrate and sodium hydroxide heated to around 140°C produces a blue finish.

This is a different process to the blue produced by simply heating polished steel parts until a blue coloured oxide film appears, and both processes are different to the bluing produced by "Engineer's" or "Prussian" blue that is painted onto parts in the workshop so that they can be marked out prior to cutting and shaping.

Back to the top of the page.


Niello or Nielled Silver

Niello is the name of a type of inlay technique where designs that have been punched or engraved into the surface of a metal object are filled with a black compound. It is an ancient technique, dating back to the Mediterranean bronze age and ancient Egyptian civilisations.

A compound of sulfides of silver, copper and lead is prepared by melting a mixture of silver, copper and lead and pouring the molten alloy into a crucible containing flowers of sulphur. Sal ammoniac (ammonium chloride) is added and the mixture pulverised. This is placed into depressions made in the surface of a metal object as a powder or paste, then the article is fired until the niello compound melts and bonds to it the surface of the object. When cool the surface is polished and the black filled areas contrast with the surrounding polished metal.

Huguenin Frères


Huguenin Frères Trademark

Huguenin Frères

Huguenin Frères Niel

One of the principal makers of niello silver items was Huguenin Frères in Le Locle, one of the principal watchmaking towns in the Swiss Jura mountains.

The company styled itself as “Huguenin Frères & C°, Fabrique Niel, Le Locle”. Beginning as makers of silver watch case, the company diversified into making other jewellery items such as badges and brooches. When stainless steel replaced silver in the 1930s for watch cases, manufacture of badges and medals became the company's principal activity.

In August 1915, Huguenin Frères were granted Swiss patent number 72290 for a secret spring for a wristwatch hunter case. These cases were used for some Rolex trench watches.

The company still exists and their web site can be visited by clicking on this link: Huguenin Frères.

Back to the top of the page.


Gold Plated Watch Cases

In the context of watch cases, ‘plaqué’ or ‘plated’ means that a core of cheaper base metal is covered with a thin skin of a precious metal to give the item the appearance of being made of the precious metal but at lower cost.

The high cost of gold means that items are most often plated with gold; in English ‘gold plated’ or in Swiss French ‘plaqué or’ (the word ‘or’ being the French word for gold).

Because a gold plated item is not made entirely of solid gold it cannot be hallmarked.

There are broadly two types of gold plating, mechanical and electrical.

Mechanical

Mechanical gold plating, usually called "gold-filled", "rolled gold" or "rolled gold plate" (RGP), is made by bonding or welding thin layers or sheets of gold with heat and pressure onto a core of base metal such as brass.

The gold plate is usually a significant thickness that will last for many years before it wears through and the base metal layer is exposed.

The thickness of the gold layer determines how long the item will last in normal use before the gold layer wears through, which is often expressed in years. Sometimes a statement such as "Guaranteed not to wear through for X years" is made, where X is a number such as 10 or 20. Sometimes just the number of years such as "10 years" is stated.

Electroplating

Electroplating is where a base metal item is suspended in bath of solvent that contains salts of the plating metal and an electrical current is passed through the solution, which causes the plating metal to be deposited onto the base item. The thickness of the plating is determined by the amount of electrical current and the length of time that it flows.

Electroplating is not suitable for depositing thick layers of material and the layer of plating is usually very thin. It can range in thickness from ½ micron (1 micron is 1 millionth of an metre; one thousandth of a millimetre or 0.00004 inches) upwards. Consequently, the quantity of gold used on electroplated items is usually so small that it is of essentially negligible cost per item.

Electroplated gold items may have the initials GP (gold plated) or GEP (gold electro plated). Different colours of gold plate, e.g. rose gold, can be achieved by using the right plating solution.

Gold is very soft, and gold plate that is only ½ a micron thick will wear through very quickly. Better quality plating of between 1 to 20 microns will last longer, and heavy electroplating of around 100 micron thickness will last a lot longer. However, any electroplated coat will wear through quite quickly, which is why no lifetime is quoted on electroplated items.

Because gold plated items are not solid gold they cannot be hallmarked. If you are buying an item that is plated and it means a lot to you or the person you are going to give it to, then find out the thickness of the layer of plating.

Back to the top of the page.


Nickel Alloys

Pure nickel looks a bit like silver with a yellowish tinge. It is a corrosion resistant metal because a protective layer of nickel oxide forms on its surface that prevents further corrosion.

Nickel was used to make watch cases either in its pure form, or alloyed with other elements that give it a whiter and more silvery appearance. The most silver-like nickel alloys are called nickel silver, although they contain no actual silver. Nickel silver is usually made of around 60% copper, 20% nickel and 20% zinc.

An alloy of nickel and copper called baitong, lterally ‘white copper’, was used in China from around 1500 BCE. This was rendered into English as paktong. The name ‘German silver’ refers to the development of a nickel silver alloy by 19th-century German metalworkers in imitation of the Chinese alloy paktong.

Nickel silver is called Argentan or Maillechort in French and Melchior in Italian (derived from the French name). The French Maillechort is named after Maillot and Chorier, who developed the alloy in 1820.

Back to the top of the page.


Pinchbeck

A gold coloured brass alloy of of three parts of zinc to four of copper called “Pinchbeck” was devised in the eighteenth century by Christopher Pinchbeck. Pinchbeck was widely used for jewellery and trinkets until the middle of the nineteenth century, when the introduction of rolled gold displaced it.

Christopher Pinchbeck (c.1670-1732) was a maker of clocks, toys and automata with a shop in Clerkenwell until 1721, and afterwards in Fleet Street. He advertised his discovery as follows, “Mr. Christopher Pinchbeck is possessed of a curious secret of new invented metal which so naturally resembles gold as not to be distinguished by the most experienced eye in colour, smell, and ductibility.”

On Christopher’s death in 1732, Edward Pinchbeck, his eldest son and sole executor, took over his father’s business. His brother Christopher became a well-known clockmaker.

Back to the top of the page.


Chrome Plated Watch Cases

Pfund advert for chrome plated watch cases, 1928
Pfund advert for chrome plated watch cases, 1928: Click image to enlarge
Erichrom advert chrome plating process, 1928
Erichrom advert chrome plating process, 1928: Click image to enlarge

The first commercial process for chromium plating was developed in 1924 in America. Chromium or chrome plating didn't come into use for watches until some time after. The first advertisements for chromium plated watch cases appeared in 1928.

One of the first case makers to advertise chromium plated cases was G. Pfund & Cie of Madretsch-Bienne, as shown by the advert from 1928 reproduced here. Other case makers who advertised chromium plated cases in 1928 were l'Usine Beau-Site, Genève and L. C. Calame of Bienne.

Another interesting advert that first appeared in 1928 was the one reproduced here for “Erichrom”, which appears to be a patented process for chromium plating that was licensed to Chromilite S.A., Accacias, Genève, André Strohl & Cie, Chromwerk, Bienne and La Centrale S.A. of Bienne, a case maker associated with Omega.

The 1930s economic depression that followed the Wall Street crash of 1929 meant that manufacturers were looking for cheaper but still eye catching alternatives to gold and silver. Stainless steel was introduced in the 1930s for the same reason

Rolex were one of the first companies to use chromium plated watch cases; Hans Wilsdorf registered the name Snowite in Switzerland in February 1927 for watch cases made from chrome plated zinc alloy.

If you have any comments or questions, please don't hesitate to get in touch via my Contact Me page.

Back to the top of the page.


Copyright © David Boettcher 2005 - 2024 all rights reserved. This page updated July 2024. W3CMVS. Back to the top of the page.