Watch Cases and CrownsCopyright © David Boettcher 2006 - 2018 all rights reserved.
This page is about the designs and features of watch cases, and the crowns that are used for winding and hand setting.
Crowns or Buttons
The round knob that sticks out from the top or side of the case and is used to wind the spring and set the hands is called the "couronne" in Swiss/French or "crown" in English.
English watchmakers and repairers sometimes use the term "button". But since English watchmakers persisted with the fusee, which made keyless winding virtually impossible, they have little claim to name the part that operates the keyless work. As button is usually used in English for something sewn on to a garment to fasten it, I prefer the term crown.
On the type of old watches that I am interested in from the time of the Great War, crowns were often one of two styles, onion or pumpkin. One often sees old watches with their crowns described as onion or pumpkin that look like nothing of the sort, which is rather confusing, so here are pictures of two crowns with my take on the terminology. It is very simple really; does the crown look more like an onion, or more like a pumpkin?
The one at the top is an onion crown. You can see how its spherical shape with the vertical grooves to grip looks like an onion. This crown is on a Borgel cased wristwatch, the shape of the crown is necessary because of the design of the stem of a Borgel watch.
The one below is a pumpkin crown. It is similar to the onion crown but more flattened, like the shape of a pumpkin.
The onion form is the older and sits neatly on the pendants of key wound pocket watches. Wristwatches don't usually have noticeable pendants, but one is necessary on a Borgel case to give depth for the spring loaded withdrawal feature. The pumpkin form looks better at the side of an ordinary wristwatch.
Savonnette and Lépine.
Watch movements and watch cases are divided into two broad categories. Savonnette watches, which in English are called "hunters", have a lid to protect the crystal. Their movements are usually laid out so that the crown is at three o'clock and the hinge for the lid at 9 o'clock. Lépine watches, which in English are called "open face", have no lid. Their movements are usually laid out so that the crown is at 12 o'clock.
This neat division lasted for centuries until the wristwatch came along. The key to the successful wristwatch was the paradoxical use of a savonnette movement in a Lépine case, which has caused confusion about the use of the two terms ever since.
Demi Savonnette or Half Hunter
Savonnette (Hunter) Watches
Savonnette cases, which in English are called "hunters", have a hinged metal lid that closes over the front to protect the crystal. When the lid is closed the shape of the watch case resembles that of a small round cake of soap with slightly domed top and bottom, called in French a "savonnette", hence the name. The English name arose because fox hunting men found it convenient to be able to open their watch and read the time with one hand, while holding the reins of their "hunter" (horse) in the other hand.
The watch in the image here is a demi savonnette or half hunter, which means that it has a little glass window in the middle of the lid so that the time can be read without opening the lid. These are sometimes called "Napoleons" because there is a story that the Emperor got so frustrated with having to open the lid of his hunter that he took a knife and made a circular cut out in the lid.
A savonnette or hunter, sometimes unnecessarily called a "full hunter" has a metal lid, without a window, that completely covers the dial so that the time cannot be read without opening the lid. They are the most robust design, but visually unattractive and a nuisance to use.
When wristwatches were created, it was obvious that the 12 o'clock should be at the top, where the strap was attached, and the crown was most convenient at the 3 o'clock position. This meant using a savonnette movement. But the principal reason for wearing a wristwatch was to make it easy to read the time, and if the watch was fitted with a lid, it either required the use of the other hand on the other wrist to open the lid, or if a demi hunter lid was fitted, the accuracy of reading was reduced. It was clear that, to be most convenient to use, a wristwatch had to be open face. The key to the successful wristwatch was therefore to fit a savonnette movement into a case without a lid.
Lépine (Open Face) Watches
Lépine or Open Face Watch
The Lépine watch was invented in the eighteenth century by Jean Antoine Lépine who radically redesigned the standard watch movement of the time to make it much thinner. Because of Lépine's role in creating the modern design of watch movement, at various times his name has been used in to name different aspects of the design. See my page about Jean Antoine Lépine for more details about this important but little known maker.
Lépine made movements thinner by moving the balance down from above the top plate into the same plane as the rest of the wheels, pivoted in the bottom plate. The top pivots of the balance and train wheels were pivoted in cocks or bridges in place of a single top plate. Lépine created this design to make watches thinner, and this style of movement was known as the Lépine calibre.
Watches could also be made thinner by not having a lid or cover over the crystal, a design called "open faced". Naturally, in his desire to create the thinnest possible watches, Lépine mostly made open faced watches and, in time, Lépine was taken to mean any open faced watch, as opposed to a savonnette or hunter watch.
Ergonomics and Movements
The layouts of movements, which gives different locations of the small seconds and pendant, which in stem wound watches carries the crown, differs between savonnette and Lépine movements for ergonomic reasons.
Savonnette watches usually have a button on the top of the stem to release the catch which holds the lid closed, and it is convenient to operate this button with the thumb, the watch being held in the palm of the hand. The lid then opens towards the fingers. Because of this, savonnette pocket watches have the dial arranged so that the pendant, the tube projecting from the case by which the watch can be suspended, is at 3 o'clock and the hinge of the lid opposite this at 9 o'clock. The small seconds display is at 6 o'clock.
Open face pocket watches are usually made so that the pendant is next to the 12 o'clock position on the dial. If a savonnette movement was used, the small seconds display would be at 9 o'clock, which somehow instinctively looks odd. So for open face pocket watches the movement was rearranged to put the arbor of the fourth wheel in line with the projected axis of the stem. This meant that with the crown at 12 o'clock, the small seconds display was at 6 o'clock. Because of its use in open face watches, which came to be called Lépine watches, this movement layout has itself come to be be called Lépine, although it was not much used by Lépine himself.
Lépine and Savonnette Movement Layouts
Pictured from the back/top of the movement
The figure here shows how to distinguish between savonnette and Lépine movements. With the stem at the top, which is the way movements are illustrated in catalogues and movement identification books, if the balance is off to one side or the other from a line projected down from the stem, it is a Lépine movement. If the balance is in line with, or nearly so, the line of the stem, it is a savonnette movement. The critical item is, of course, the location of the fourth wheel, but it is much easier at a quick glance to locate the balance.
Distinguishing between savonnette and Lépine watches is, of course, simple. If it has a lid, it's a savonnette; if it doesn't have a lid it's a Lépine. But what about an open face wristwatch with the crown at three and the small seconds at six, is it a Lépine or a savonnette? In fact it's neither; it's a wristwatch!
There are several meanings for Lépine in watch terms:
- A bridge or bar movement with the balance in the same plane as the train wheels.
- An open faced watch.
- A watch movement with the arbor of the fourth wheel in line with the projected axis of the stem.
- A movement layout where the small seconds is at 6 o'clock and the pendant or crown is at 12.
When the wristwatch was created it was natural to arrange the dial with the 12 at the top and the crown at 3 o'clock for both convenience of access for winding and for attaching the strap. This of course is a savonnette layout. But giving a wristwatch a lid would have defeated one of the principal benefits of a wristwatch, that it was possible to look at the time without using both hands, so wristwatches were almost universally open face.
The key to the successful wristwatch was therefore the paradoxical use of a savonnette movement in a Lépine case.
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Converted Pocket Watches
Sometimes it is written that "early wristwatches used small pocket watch movements", or even "early wristwatches were converted pocket watches". These statements are not true. Although it seems logical to assume that the wristwatch started in this way, and then purpose made wristwatches came along as a later development, this is just that; an assumption, and it is wrong. There was nothing difficult about designing or making a wristwatch, and when the demand arose this is what happened; manufacturers made wristwatches. It is in fact more difficult to convert a pocket watch into a wristwatch
There undoubtedly were some conversions of pocket watches into wristwatches, these were often not done by a watch manufacturer but in the aftermarket, and often done pretty badly. Conversions of pocket watches into wristwatches by the simple method of soldering on two wire lugs as mockingly described by Jaquet and Chapuis in The "Invention" of the Wristwatch are not nearly as common as people sometimes think.
In fact, converted wristwatches did not precede purpose made wristwatches, conversions were done during the Great War when the supply of wristwatches could not keep up with the demands of newly commissioned officers desperate to get to the front before the war was over.
The Practicality of Conversion
Wrist watches don't usually have a lid as a hunter watch does, that would defeat the point of strapping the watch to a wrist to make it easy to read. If it had a hunter lid, you would still have to use both hands to read the time. For this reason the vast majority of wristwatches are open faced. If a pocket watch was converted into a wristwatch, it would have to have already been an open faced pocket watch. How easy was this?
If I soldered on a couple of wire lugs, would this really be a wristwatch?
Here is a picture of a small open faced Borgel pocket watch that I have rotated to bring the crown to 3 o'clock as if it were a wristwatch. A couple of problems with this as a wristwatch are immediately apparent.
- The number 12 is next to the pendant, in the wrong place for a wrist watch.
- The sub seconds dial is next to the nine, again in the wrong place for a wrist watch.
- The long pendant carries the bow to which a safety chain is usually attached.
- There is engraving on the back of the case (not shown).
Pocket watches converted to wristwatches usually show signs of all these problems. The 12 is often in the wrong place, or the dial feet have been cut off so that the dial can be rotated. The bow has been removed and the pendant and winding stem cut down, usually quite obviously. The position on the sub seconds display cannot be moved and would still appear at 9 o'clock, so often watches were chosen that have no seconds display. Nothing is done about the engraving on the back of the case, which is a dead give away that the watch left the factory as a pocket watch.
This sort of mucking about is just far too much trouble to be the way the first purpose made wristwatches were made. It was a very simple idea to attach two wire lugs to a case to take a strap or a bracelet, and ladies' wristwatches with bracelets had been made since the late 1880s. Purpose made men's wristwatches appeared much earlier than many people think, around 1900, but there was no demand for them from men. My earliest wristwatch with a verified date was made in 1905 by IWC with a Calibre 64 savonnette movement put into a purpose made Lépine (open face) wristwatch case, ordered from Borgel in Geneva in September that year. So purpose made wristwatch cases were readily available in the early 1900s, there was no need to "convert" anything.
Although there are undoubtedly some wristwatches that were made by soldering wire lugs onto a small pocket watch, these are usually pretty obvious and not very well adapted to their new role. From their appearance it seems they were usually done by a local jeweller who was not used to the work; some of them even look like they might have been done by the village blacksmith. My research indicates that these conversions were done during the early years of the Great War, when everyone taking a commission as an officer was expected to have a wristwatch. There was such a demand that the supply of wristwatches couldn't keep up and some fob watches were converted into wristwatches for officers determined to kit up and get to the front before the fighting was over, which in 1914 it was expected to be by Christmas.
IWC Fournitures 1917: Lépine (open face) versus Savonnette (hunter) et (and) Montres Bracelet (open face wristwatches) movements.
The key to the successful wristwatch that many people fail to grasp was the paradoxical use of savonnette (hunter) movements in Lépine (open face) cases. For more details about the difference between Lépine and savonnette movements, see Savonnette vs. Lépine.
Instead of messing about converting pocket watches, a manufacturer wishing to make wristwatches would take small savonnette movements that they were already making and put them into purpose made open face cases with short pendants and lugs for a strap and, hey presto, wristwatches!
Was putting a small savonnette movement into an open face case that had been purpose made to take a wrist strap really a "pocket watch conversion"? No of course it wasn't.
This use of savonnette movements in open face cases, which for centuries had been called Lépine cases, gave rise to a new terminology. This is shown in the image here taken from an IWC catalogue of spares (fournitures) published in 1917.
The calibre 63 on the left is described as a Lépine, a movement with the fourth wheel in line with the axis of the winding stem which is suitable for an open face or Lépine case. The calibre 64 on the right is described as a "savonnette et montres bracelet", a movement suitable for a hunter case with a lid, and for open face wristwatch.
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Watch Cases with Two Backs, or Double Bottoms
Double Case Back
One of the questions I am occasionally asked is "Why does the case have two 'backs'?". This is where a case has a hinged back that opens to reveal an inner back or cover, sometimes called a "cuvette", which is itself can be also hinged and opened to reveal the movement, or fixed to the band or middle part of the case in a double bottomed dome or Consular case.
This case design goes back to watches that were wound from the back, and some set from the back, with a key. Each time the watch needed to be wound or have the time set, the back was opened and a key with a hollow square end was applied to a square end on either the mainspring barrel arbor and turned to wind the mainspring, or to a square on a friction post that ran through the centre arbor and carried the minute hand and was turned to set the hands. If there were no protection for the movement, then a clumsy person could accidentally press the key into the watch mechanism and damage it.
In the earliest watches the movement was set into a case or "box" that had a hole in the back for the winding key. Sometimes this hole was covered by a little shutter to prevent dust entering, which was pushed aside to allow winding. This was not an entirely satisfactory arrangement, and watches usually had a second out case to protect the inner case. This arrangement was called a "pair case". The inner case of a pair case has a hole for the key to pass through to wind the spring, and the outer case then covers this hole.
The style conscious French nobility were never particularly fond of the bulky pair case, and the fashion that began in France around 1775 for close fitting waistcoats resulted in them abandoning it altogether. Jean Antoine Lépine fitted his watches with single cases with no hole in the back. The watch was wound through the dial, which spoiled its appearance and exposed the enamel to damage by the key of a clumsy owner.
To avoid the need for a winding hole in the dial, Lépine designed a case with a middle part, called the "band", to which the movement was fixed. A bezel carrying the crystal was fixed to the front of the band, and to the back were hinged two covers, an outer and inner. The outer cover is usually called the bottom or back, the second the inner cover or cuvette. The cuvette had one or two holes for the key, one offset from the centre for winding the mainspring, a second in the centre if the hands were set from the back.
Lépine invented hand setting from the back of the watch, boring the centre arbor so that a centre post that carried the minute hand could be passed through it, driven by friction between the two. The cannon pinion is mounted on the centre post. When the hands were set from the back there was no need for the front bezel to open and it was made to simply snap on, doing away with the need for a hinge at the front for the bezel. The movement was fixed to the band, eliminating the hinge for the movement to be swung out from the front of the case.
The case invented by Lépine, with the movement fixed to the band, snap on front bezel and two hinged backs, is sometimes attributed to Breguet, who later used the same design. Breguet usually made the inner cuvette of gilt copper or brass, and only made it of gold in watches of his top quality, ‘ouvrage premiere classe’. It thus became the standard practice in France to make the cuvette of base metal, except in the best quality work.
In English watches the inner cover, which was called the dome, was regarded as part of the watch case by the assay office, whether it was fixed to the band or jointed (hinged) to it in a Lépine style case. Because of this the dome had to be made of the same standard of metal as the rest of the case, e.g. 18 carat gold or sterling silver, or none of the case would be hallmarked by the assay office.
Like Breguet, Swiss makers did not regard the inner cuvette as part of the case, after all it was only there as a barrier to prevent a clumsy owner damaging his watch and was not seen when the back was closed, so they allowed it to be made of base metal. This was often plated with gold or silver to tone with the rest of the case, but marked "metal" or "cuivre" (copper) so that it could not be not mistaken for precious metal.
In later movements that were wound and set by the crown, the holes in the cuvette for the key were not needed, but it was retained for better quality watches. This may have been partly because of tradition, a sign of quality workmanship not found in cheaper watches, and it might give better protection against the ingress of dust than a single case back.
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Early pocket watches have "pair cases", two cases one inside the other. Sometimes a third case was provided, usually of a non-precious material such as leather, to protect the outer of the pair cases.
The image here shows an English pair cased watch with a fusee verge movement. You should be able to make out the cone shaped fusee between the plates of the movement, on the right behind a pillar. The wheel in the foreground with teeth pointing downwards is the contrate wheel, a sure sign of a verge movement.
The case on the left is the outer case of the pair. It is sterling silver and has London Assay Office hallmarks for 1844 to 1845, but there is no sponsor's mark. The cut outs in the rim are for the pendant, which is attached to the inner case. The rusty iron strip is the spring for the catch that normally holds the case closed.
The inner case has the same London Assay Office hallmarks as the outer case, and a sponsor's mark of the initials JB over WW struck incuse without a surround. This mark was entered on 27 June 1834 by Josiah Barnett & William Walters in partnership at 15 Lower Charles Street, Northampton Square, Clerkenwell.
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Consular, Double Bottom, and Dome Cases
The definition of what constitutes a "consular" watch case is not clearly laid down in any reference that I have found. The name consular is sometimes used for the cases of English lever watches that have a jointed (hinged) bezel and back with a second, fixed, inner back called a "dome". I believe that this is incorrect.
In "The artistry of the English Watch", Cedric Jagger says The consular case - which is said, traditionally, to be associated with Napoleon's appointment as First Consul, even if the dates do not actually match up, - seems first to have been introduced by the precision watchmakers in c1775. Essentially, it is a single case with a double back, the outer of which is opened for access to the winding and hand setting squares, while the movement hinges out from the front." The government of France was called Consulate after the fall of the Directory in 1799 until the start of the Napoleonic Empire in 1804. Executive power was vested in three consuls. At first these were equal in authority, but Napoleon quickly consolidated power in himself as "First Consul".
This description of a single case with a double back would seem to apply to the cases of English lever watches, and several sources point in the same direction. Both Britten and de Carle imply that the terms consular and double bottom are synonymous, as does Terence Camerer Cuss in the glossary to "The English Watch: 1585 — 1970".
However, I noted that David Penney described on his web site that the case of Pennington watch No. 5443 has an "18ct gold case of true consular form, the band and both covers all pivoted on the same joint". David told me that in his view the distinctive feature of a consular case is that the front bezel and the case back are connected to the middle part of the case by a single "joint" (the casemaker's term for a hinge). The knuckles soldered to the bezel and case back, and the tubes or "charnières" soldered to the case middle part sit alongside each other and are all connected by a single pin.
After David explained this to me I went through Terence Camerer Cuss's book again and I noted that all the cases that are described as consular are in the chapter 1775 to 1825 and have the single joint feature, whereas later cases with separate joints for the back and bezel are called simply "cases". This confirmed to me that David's description of the single joint as the principal distinguishing feature of a consular case must be correct, although this doesn't appear in any book that I have seen.
The use of a single joint to hold the back and bezel to the middle part of a consular case is quite distinct from the later cases used for English lever watches that have separate joints for the back and bezel. I don't have any watches with consular cases but examples can be found on David's web site at David Penney's Antique Watch Store.
The consular case appears to be the first evolution of the pair case. The glass of a consular case is mounted to the bezel of the outer case, rather than a bezel on the inner case of a pair case watch. The bezel of the the inner case was discarded. The remaining half of the knuckles of what had previously been the joint between the bezel and the band and back of the inner case of a pair case watch were integrated into the joint of the outer case. The movement remained hinged at 12 to the vestigial inner case, which was now the case middle part with a fixed inner back.
French watches were sometimes wound through a hole in the dial and the hands set by turning them with a key on a square boss of the minute hand or centre arbor, so there was no need for the owner to access the back of the movement, so their cases had a single back or bottom fixed to the middle part of the case. Putting the winding hole through the dial was rather unsightly and often resulted in the enamel of the dial being damaged by the key. However, having only a single bottom meant that the case was as slim as it could be, which the current French fashion of the time for tight fitting waistcoats preferred. There doesn't appear to be a well defined name for this style of case, but Jean-Antoine Lépine of Paris was the pioneer of slim watches at the time. Open faced watches are generally known as "Lépine" watches, perhaps the design with a single bottom was the definitive version.
English Lever Cases
English watches usually wound from the back and had an enamel dial that was unmarred by a key hole, although they were generally set from the front by a key applied directly to the square boss of the minute hand.
Winding from the back necessitated a hole in the case for the key which needed to be covered to prevent dust getting in when it was not being used. This was the reason for the original pair case. The inner case of the pair had the hole, which was covered between windings by the outer case. Pair cases were not well sealed. The inner case carried the bezel and glass, the front opening in the outer case was open. This meant that dust and fluff could find its way into the outer case and between the two cases round to the winding hole. Nevertheless, pair cases continued to be made, mainly for watches with verge escapements, into the late nineteenth century.
When the English lever watch was developed around 1820 a better case design was also adopted. Like the earlier consular case, an outer bottom or back was hinged and when opened revealed an inner cover, called in English watches the "dome", which was fixed in place to the band or middle part of the case. The dome has either a single hole for winding, or two holes if both winding and hand-setting are from the rear. The glass is held in a bezel, and the outer back and bezel are attached to the middle part of the case by joints.
Unlike the consular case, the joints for the back and bezel are separate and located at different positions around the case middle part. This made them simpler, with fewer knuckles, which allowed them to be made smaller and less obvious. It would have been easier to make these simpler joints, but a challenge to solder all the charnières to the middle part of the case at the same time. This was probably the reason why they were in separate locations around the case middle part, so that they could be soldered in two separate heatings.
The movement is attached to the middle part of the case by a hinge at 12 o'clock. If it is to be examined or regulated the movement is swung out from the front of the case by first opening the bezel and then releasing a catch which holds the movement in place. The bezel is usually hinged at the side around 9 o'clock. The catch is below the six o'clock position on the dial, with the movement hinge at 12 o'clock. To fully remove the movement from the case, the hinge pin is pushed out. The practice of hinging the movement to the case continued in some high class English watches until about 1870.
The name of this style of case does not seem to be well defined. When I first bought an English lever watch I was told that it was a consular case, but thanks to David Penney I now realise that this is not the correct name. In his book "Watch and Clock Making", David Glasgow calls them "double bottom cases" and says that their cost was part of the reason for the decline of English watchmaking. However, I have also seen them called "dome" cases in nineteenth century sources. The term double bottom is rather generic and could apply to cases with a jointed inner back, whereas dome refers to the specific fixed inner back used in English lever watches, which seems to be preferable.
The first photograph shows an English lever watch. The front bezel with the crystal has been opened and the movement swung out of the case on a hinge located at 12 o'clock below the pendant. The small projection from the edge of the movement that I have ringed in red is the catch that normally holds the movement in place when the bezel is opened to set the hands, you press it with a finger nail to release the movement so that it can be swung out.
The outer back or case bottom is also open, showing part of the hallmarks for sterling silver. Inside the case you can see the dome, also hallmarked, that is fixed to the middle part of the case. In this watch the dome has a single hole for winding, which is isn't visible in the photograph.
In English watches, if the case is gold or silver the dome must be made of the same metal, because if it was not, none of the case would be hallmarked. English assay offices would refuse to hallmark an item that was not all of one standard of metal.
The second photograph shows the cap that covers the movement. The curved blue steel spring engages with two pillars on the movement (in the picture one of these is missing) to hold the cap in place. To release the cap you slide the blue steel spring round and the cap will then lift off.
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Swing Ring Cases
Swing Ring case 1931
The swing ring case was invented by Ezra Fitch in 1879 as part of the design of a waterproof case, see Fitch Swing Ring Case. Fitch's case had a carrier for the movement that was hinged to the case so that the movement could be swung out from the front and there was no need for a separate case back. This is the swing ring element. A screw down front bezel made the remaining front joint watertight. The entrance to the case for the stem was sealed by the simple expedient of a cap that completely enclosed the crown and stem and screwed down onto the end of the pendant.
The swing ring part of Fitch's design proved to be surprisingly long lasting. The image here is taken from Robert Pringle & Sons "Wilderness" catalogue for 1932. It is from a page marked "Special Dust and Waterproof Watches". The page includes Borgel, screw back and bezel and hermetic watches, and also a cushion shape watch by Helvetia with "a patent device for rendering the stem watertight".
The swing ring watch is also marked Helvetia on the dial and has a 15 jewel lever movement with shock absorber. However, there is absolutely no provision for sealing the slot in the case side that the stem drops in to, and because the case is a cushion shape the bezel snaps on. This watch has no waterproof features and should not have been on this page.
Watches with swing ring cases are sometimes called "semi-hermetic" because they often have a fluted screw down bezel and look superficially like some watches with waterproof cases such as the Borgel screw case or the Finger/Gruen Hermetic. But if they don't have any means of preventing water entering the case where the stem passes through they are not even remotely hermetic and should not be called such.
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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 grey of the underlying steel.
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.
Jean Finger advert 1894
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 oxidise watch cases for manufacturers who don't have the capability to do it themselves.
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 true 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".
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.
Pictured right is an advertisement which 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.".
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 mechanism 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 mechanism 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 mechanism 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 oxydised 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.
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Gold Plated Watch Cases
The are broadly two types of gold plating, mechanical and electrical.
Mechanical gold plating, called "gold-filled", "rolled gold" or "rolled gold plate" (RGP), is made by bonding with heat and/or pressure thin layers or sheets of gold onto a core of base metal such as brass. The thickness of the gold determines how long the item will last in normal use before the base metal shows thorough, which is often expressed in years. Sometimes a statement such as "Guaranteed not to wear through for X years" is made, sometimes just the number of years such as "10 years" is stated.
Electrical plating or electroplating is where a base metal item is suspended in bath of solvent that contains salts of the required plating metal and an electrical current is passed through the solution, which causes the plating metal to be deposited onto the base item. Different colours of plating, e.g. rose gold, can be achieved by using the right plating solution. The layer of plating deposited 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. The quantity of gold used on electroplated items is so small that it is essentially negligible and costs very little.
Electroplated gold items may have the initials GP or GEP. 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. 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 about the quality and in particular the thickness of the layer of plating.
Because plated cases are not solid gold they cannot be hallmarked.
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Chrome Plated Watch Cases
The first commercial process for chromium plating was developed in 1924 in America and chrome plate didn't come into use for watches until some time after then. Rolex were one of the first companies to use it, Hans Wilsdorf registered the name "Snowite" for watch cases that were made from chrome plated nickel. The 1920s economic depression that resulted in 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
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Watch Case Repairs
If you have a watch case that needs repairing, get in touch with my good friend Adam Phillips. Adam is a goldsmith with over 30 years experience in the making and repair of all types of watch case, from antique pocket watches to modern wristwatches. He was originally based in Clerkenwell, the historic centre of watchmaking in London but now his workshop is in Chesham, Buckinghamshire. Adam can undertake all types of watch case work, e.g. new watch backs clip, screw, or hinged, bezels in any material and shape, hard gold plating, gilding, rhodium plating, chrome and nickel plating, He can also copy parts.
Contact Adam via his web site: www.watchcaseworks.co.uk - this link will open in a new tab.
Copyright © David Boettcher 2006 - 2018 all rights reserved. This page updated July 2018. W3CMVS.