1955 Automatic K-375

If you've studied Hamilton's 1950's and '60's watches closely, then you've probably picked up on the rationale behind the numbers used when Hamilton named Automatic models.  100-series watches were solid 18K gold.  200-series were solid 14K gold.  300-series and 400-series are solid 10K gold and gold filled, respectively.  500-series are stainless steel and 600-series are rolled gold.

Add to the nomenclature that if the second digit is a 5, then the back is likely stainless steel.  So a K-150 is an 18K solid gold watch with a stainless steel back.  A K-451 is 10k gold filled with a stainless back.

Makes sense... right?

Well - almost.  There's one model that is a bit of a mystery, that being the 1955 Automatic K-375.  It was produced for four years.

If you look closely, the K-375 catalog says it's 10K yellow gold overlay.  That's the mystery... what exactly is "gold overlay"?  You'll see more about that below.

The back is stainless steel.  That's not terribly unusual, After all, there are even 100-series 18K watches with stainless steel backs too, for example, the 1955 K-150.

Like most high-end Hamilton watches, the K-375 offers solid 18K gold numerals and markers on a silver dial.

Behind the dial is a Hamilton 661 automatic movement.

I recently picked up a K-375 project watch.  It arrived in decent condition, just a faint radium burn from the lume on the hands.  I suspect the watch was tucked in a drawer for quite a few years, stuck at about 5:45.

The back of this watch has two parts; a pie pan-shaped cover held in place with circular ring.

Here's the second part of the mystery... the inside of the case back is stamped "10K G.F. Bezel"  Why would Hamilton stamp the inside of the case back gold filled, put gold overlay in the catalog and name the watch a 375?  Why not make is a 400-series watch?  Weird, huh?

The best I can guess, and it's a total guess, is that gold overlay contains substantially more gold than gold filled.  Gold filled usually implies about 5% of the thickness of the material is a layer of gold, while the remainder is a base material (brass, or some other alloy).  When you see "1/20 gold fill", the 1/20 implies 5%.  If it was 1/10, the gold content would be 10%, etc.

I just overhauled a 661 in a K-250 yesterday, so I'll spare you the details again.  However, this one was a little more challenging as it took me several attempts at cleaning the balance assembly before I could get it to run cleanly, as shown below on my watch timer.  A clean-running watch is represented by two, fairly close, parallel running lines.  Ideally the two lines would be horizontal.  Trending upwards means the watch is running fast... in this case 27 seconds per day fast.  I find recently overhauled watches will settle down after a little while, so I leave them running slightly fast.

With the dial and hands reinstalled, I can put the reassembled movement back in the case.  The oscillating weight, aka rotor, can go back on now.  One additional insight into the mystery of the case material is that there is absolutely no sign of verdigris on the case.  Verdigis is the green "rust" that you see on gold filled cases where the base material comes into contact with moisture.  Solid gold cases never show verdigris since only gold is present.  This watch's case is a clean as a solid gold case.

Although the Speidel bracelet isn't original to the watch, I don't have any 18mm straps at the moment to install on it.  So the bracelet will have to do for now.  It looks pretty nice though - so maybe I'll keep it.  I think the watch cleaned up very nicely.  I removed the radium from the hands in my ultrasonic cleaner so there will be no more damage to the original dial.

The K-375 is a sharp looking watch, don't you think?

1955 Automatic K-250

The 20th century introduced a number of "revolutionary" materials that were great advancements for mankind.  "Miracle materials" like asbestos were used in all sorts of common places.  Only after years of exposure would we collectively realize that maybe they weren't so great after all.

Another miracle material was radium.  Radium is a naturally occurring element.  In fact, many areas have radium-derived radon gas seeping to the surface of the earth and it's a common thing to test for when you buy a new house.  Now days radiation is something most people are very concerned about but back in the mid-twentieth century it was used for all sorts of things... including toothpaste and suppositories to improve your sex drive.  Marketers of radium-containing products lauded the restorative powers of their products... the consumption of radium meant that "every tissue, every organ in the human body is bombarded with it's health-giving electric atoms".

Well, apparently it will also kill you.

Radium was also used as a paint and the radiation that it emits reacted with other material in the paint to make the material glow, 24x7.  It was a perfect solution for things like clocks, signs or other indicators that you might want to see in the dark.  Although eventually the glowing material in the paint burns out, don't worry... the radiation sticks around for 1,600 years.

Pretty scary, right?  Well, don't be too alarmed.  First of all, the radiation is easily blocked by glass, your skin, etc. so the main concern you should have with radium is that you don't consume it.  Radon is a gas - so the concern with radon is breathing it in - sort of like smoking.  Everyday exposure to the gas could cause health concerns down the road.  (proper venting of basements and crawlspaces dramatically reduce the exposure risks).

Anyway - like all other watch manufacturers, Hamilton used radium paint on models with luminous features (hands, markers, etc).  Usually the lume was visible so you could see the elements glowing in the dark.  However, in the 1950's there were a number of models that featured "silhouette hands" - where the radium was applied to the bottom of the hands - and it cast a glow onto the dial and backlit the hands as a silhouette.  

An example of one of these models is the 1955 Automatic K-250.  It was produced for three years.

One of the problems today with silhouette hand-models is the dials are often burned by the close proximity to the hands.  Of course, you'll see that with any of the luminous watches.

The K-250 came in a 14K solid yellow gold case with a  stainless steel back.  The silver embossed dial has 18K gold numerals and a pearled track.  Tucked inside the case is a Hamilton 661 automatic movement.  This 17 jewel grade was made by the Swiss-maker, Kurth Freres.  It's a very common model is just about all of the K-series watches.

My K-250 project watch arrived in fairly nice condition.  The crystal was pretty beat up but otherwise it looks very promising.  The strap it came with is obviously a little too narrow.

The stainless steel back screws off of the case and it has been roughed up for some reason.  I suspect it must have had an engraving at some point and it was removed.  I'd rather see an engraved watch than a watch without engraving, but that's just my personal opinion.

The 661 inside is in fine condition.  It seems to run okay but I'm sure a trip to the spa will do it a lot of good.

Without the crystal in the way, the dial looks surprisingly good.  It may have been redone at some point in it's life but if it was, it was a long time ago.

There are a lot of parts to an automatic.  They're all cleaned up and ready to be reassembled.

Without the oscillating weight and it's carrier installed, the movement looks like your garden-variety manual winding movement.  It's now happily running and ready to go onto the timer.  You can see that this model has a large train bridge that covers the majority of the back of the watch.  It can be a little tricky to get all the wheels lined up at once so the bridge will fall into place.

It's running just fine, without any tweaking whatsoever.

A new crystal is an inexpensive way to dramatically improve a watch's appearance.  I almost always replace the crystal with a fresh one - although slightly-used plastic crystals can also be polished easily to look like new.

The movement, sans-weight, is reinstalled in the case along with it's movement ring to hold it securely.  I like to put the oscillating weight on last - as it's a little harder to handle when it's installed outside of the case.  This way, everything is nice and secure.

A better-fitting, genuine lizard strap completes the restoration.  I removed the remaining radium from the back of the hands using my ultrasonic cleaner.  So although the dial still shows a very faint radium burn, there will be no further damage.  The silhouette aspect of the watch has been lost to time and modern luminous material doesn't work the same way - so I'll just have to enjoy looking at this watch in the light.

1948 Chatelaine

There are a couple of men's models that used ladies watch movements, the earliest being the 1936 Norfolk. But there is only one woman's model that used a man's movement.  In fact, I think the record for the model with the longest production run is the same woman's model... the 1948 Chatelaine.  It was produced for an uninterrupted 15 years and produced through through 1963.

Originally the Chatelaine was produced with a 17 jewel 987S movement, left over from WWII production.  The case was rhodium plated sterling silver.  Rhodium is a precious metal, silver in color, and more precious than gold.  The black numeral dial should look familiar - it's similar in pattern to the men's Secometer model, although the orientation is different with the stem at 12:00.

The following year the Chatelaine was given the newly introduced 18 jewel 748 movement.  The case also lost the rhodium plating and was simply sterling silver from 1949 on.

The Chatelaine was meant to be worn, either as a necklace or a broach.  The model was specifically advertised for "Nurses and Nuns" and I've seen many Chatelaine examples that were engraved as presentations for school sisters of various orders.

In 1961, the Chatelaine II joined the Chatelaine in the model line up.  The "II" model is very similar to the original with the exception being it utilized a 17 jewel Swiss-made movement instead of the 18 jewel 735 American-made grade then in production.  The two watches were produced together through 1963, after which only the Chatelaine II was available.

Finally, in 1968 and 1969, the Chatelaine II was replaced by the Chatelaine III with yet another Swiss-made grade.  The one constancy through all three models is the sterling silver case.

I find it interesting that the Chatelaine didn't receive a B-model designation when the movement changed from 987S to 748 and then to the 735.  B models usually mark a change in movement calibre but perhaps the 987S to 748 preceded the practice of using a B to denote a change.  Plus, the 748 and 735 are largely considered identical other than the balance jeweling - so that may not have been a big enough change to warrant a B.

In any event, 15 years of production is a record rivaled only perhaps by the Boulton.  The Boulton was introduced in 1940 and produced through 1954 - a long production run for sure - but it was interrupted by WWII so the record really belongs to the Chatelaine.

I recently picked up a Chatelaine since the price was right and it was an opportunity to show it on my blog.  They're wonderful watches and make great gifts, in my opinion.

As received, my example is probably from the late 1950's or early 1960's - as it has a 735 movement. From the outside, there are no obvious differences between the models - although the 987S has a little less silver since the movement is slightly larger.

The case is a three-piece design - making it also the last Hamilton model to use a three-piece case (if you exclude models with purely decorative bezels that can pop off).  The Chatelaine has a case back and a front bezel that snap onto the case center.

The 735 is an upgraded version of the 748.  It's interesting to note that originally the 748 had a one-piece barrel bridge - so you had to take the watch apart to get to the mainspring, in the event that it broke.  Within a couple of years, Hamilton changed the 748 and added a two-piece barrel bridge - so you could remove the portion that covered the mainspring barrel, without having to remove the train bridge.  I'm sure that was a huge timesaver for watchmakers.

The two-piece bridge design was carried over to the 735 movement when it replaced the 748 in 1955.  Eventually, however, Hamilton went back to the one-piece bridge design for some reason.  I guess the advent of "unbreakable" white alloy mainsprings meant the added cost of a two-piece bridge was no longer necessary.

If you want to see the two-piece design, compare the photo below with the 735 in my recent Guardsman III post.

Without the bezel in place, the movement and dial will come out the front as soon as I remove the crown and stem.

Sterling silver was used in a number of watch cases but not too often.  The Chatelaine is definitely the most commonly found silver model, that's for sure.

The movement is completely disassembled and cleaned.  Once everything is dry, it can be reassembled with fresh lubrication.

A slight tweak to the regulator slows the watch down until the two lines approach horizontal, representing 18,000 beats per hour or 5 ticks per second.

The reassembled movement gets the dial and hands reinstalled and then everything is tucked back into the case.  The sides of the crystal give the watch a little of a gold-fish bowl effect so you can't see the seconds markers on the outside of the dial from straight on.

The dial can be installed with the 12 up or down so you could orient it with the 6 at the stem and thus make it easier to read if it was hanging from your neck.  The 12-up is the traditional orientation of the dial though.  The bow swivels 360 degrees so if you installed it on a chain it would still lay flat.