Wednesday, December 7, 2011

How to Put On and Wear a NATO Watchstrap

This is our second how-to video. While our first dealt with how to safely install any nylon strap without causing it to fray, this one deals specifically with the mysteries of the NATO G-10 watch strap -- you know, the one with that odd little extra piece of nylon. Please enjoy.

Friday, December 2, 2011

How to Properly Install a Real Bond Nylon Watchstrap

Once in a while we get an email from a customer who complains that his or her Corvus Real Bond Watchstrap has begun to fray along the edges. Sometimes the comment is even that the edges became frayed right after putting the strap on their watch.

Fraying along the edges of the Corvus Real Bond (or any nylon) watchstrap is always caused by the edge of the nylon scraping agains the watch lugs when the strap is slid between the lugs without first removing the springbars.

We have put together a video tutorial on how to properly put a NATO or other nylon watch strap on a watch:

The lugs of many watchs, especially military-style watches (such as our Corvus Bradley Dive Watch) are quite sharp. When you pull a nylon watch strap through without removing the springbars, it is like taking the edge of a knife and scraping it against the edge of the nylon. In these cases, even a brand-new strap will fray.

We recently reviewed a number of videos on YouTube, etc. on "How to install a NATO watchstrap." All of them are wrong, and give dangerous advice. You must carefully slide the nylon between the lugs, while pinching it so that the edges do not scrape against the lugs.

Many of the cheaper copies of the NATO watchstrap design are made of backpack webbing. This has a low thread count, and thick nylon thread. This stiff, uncomfortable webbing is is made to be quickly pulled through D-Rings and other hardware.

Corvus watchstraps are made of supple, high thread-count nylon, woven specifically to wear on your wrist. A little care when putting the strap on and taking it off your watch will result in a strap that will look great for years. Members of our staff have been wearing the same Real Bond straps every day for over three years and they still look good.

Sunday, November 20, 2011

The Untold History of the Bonklip Watch Bracelet

Bonklip watch bracelets were first developed in the late 1920's and the early 1930's, and are widely associated with the Royal Air Force and British military watches in general. The primary link with the RAF is that the easily adjustable bracelet was issued to post-WWII aircrews to wear on their legendary Mark XI navigation watches. These were made for the RAF by Jaeger-LeCoultre and IWC, and are two of the most accurate mechanical watches ever made.

The Bonkip watch bracelet was an innovative design for several reasons. It was one of the first mass-produced and relatively cheap watch bracelets to use stainless steel (examples are variously marked "Firth's Stainless" and "Staybrite," a trademark for the 18/8 stainless steel invented by Thomas Firth of Newcastle, England in 1924). Second, the bracelet was easily and quickly adjustable to virtually any size.

The Bonklip bracelet's association with the British Military has been well documented by Adrian van der Meijden and Thomas Koenig in their article: The Bonklip Bracelet in his Majesty's Service, Horological Journal, December 2007. The Mark XI navigational watches are covered comprehensively in the article Man is Not Lost, Horological Journal, January 2004. In general, however, virtually nothing was known about the Bonklip itself until now.

The Krementz Self-Adjustable Watch Band

The Bonklip design may not have been a British invention at all. Although an English patent was applied for by Dudley Russel Howitt on March 6, 1930 (and later granted), an American patent application was filed for virtually the same design on April 10, 1929 by Walter M. Krementz.
Walter Krementz was the son of George Krementz, who founded the Newark, N.J. jewelry company Krementz & Co. in 1869. The company became successful by pioneering the technique of sandwiching base metal between two sheets of real gold, resulting in "gold-filled" or "Rolled Gold Plate" jewelry, a superior alternative to electroplating. Their big breakthrough was in selling gold-filled collar-studs, a now obsolete piece of jewelry used to fasten the removable starched collars used on men's shirts until the First World War.

Krementz Factory in Newark, N.J.

By 1929, Walter and his brother George, Jr. ran what was probably the world's largest jewelry company, and sold a full line of watch bracelets. A 1929 advertisement shows Krementz watch bracelets for men, that used "tubular mesh bands" and "open link mesh bands" identical to the later Bonklip-style bracelets, except with conventional folding clasps, and without the length adjustability.

However, on April 29, 1929, Walter filed a U.S. Patent application for a "Wrist Watch Bracelet" that utilized the open-link mesh band of their earlier products, and combined it with the fold-over adjustment loop and universal attachment clip that made the Bonklip so popular.

A patent was granted to Krementz & Company and the bracelet -- virtually identical to the later Bonklip -- was on sale at least as early as 1931. 

Krementz self-adjustable watch bands were marked "Krementz, Pat. Oct. 1930, "Kremaloy". The Kremaloy seems to have been a type of stainless steel. Surviving examples are  still completely rust-free. $3.50 was the equivalent of about $60 today, after adjusting for inflation, although this is misleading as this 1933 ad was from the height of the depression. At the time this ad appeared, the average daily wage in the USA was only about $30 in today's dollars. Two days wages; not a cheap product.

The Krementz bracelets seem to have not been terribly popular. Far fewer survive than the Bonklip, and although Krementz dominated the costume jewelry market until the 1970's, no post-WWII bracelets of this type appear to have been made. In the 1950's and 1960's, after the Kementz patent expired, another American company, Forstner, made a very similar product for a number of years. These Forstner bracelets are quite common, many in new old stock condition.

The Success of the Bonklip

Meanwhile, on the other side of the Atlantic, eleven months after Walther Krementz filed his U.S. Patent application, a Londoner, Dudley Russel (sic) Howlitt filed a British Patent application on April 6, 1930 for an almost identical invention. Howlitt followed this up in August, 1930 with a German Patent application. Both patents were eventually granted. While the Krementz bracelet would largely be forgotten, Howlitt's product, sold as the "Bonklip," would become famous.

Dudley Howlitt was one of six children of Harry and Francis Howlitt. He worked in the thriving jewelry industry in the Clerkenwell district of London. There is some evidence that he may have at one time been a silversmith and made and sold Sterling silver cigarette lighters under his own name and with his products bearing an "HRH" maker's mark along with London Hallmarks. 

Sterling Silver cigarette lighter possibly made by Dudley Russel Howlett
What is certain is that at the time he patented what was to become the Bonklip watch bracelet, he was associated with the Birmingham jewelry company B.H. Britton and Sons, and worked out of their London offices at New House, 67-68 Hatton Garden, London. The New House was an office building right in the center of the Jewelry District in Clerkenwell, just north of the City. It still is a handsome building today, and the entire district has enjoyed a resurgence in the past few decades.

Former location of the London offices of B.H. Britton and Sons as it looks today
B.H. Britton and Sons manufactured the Bonklip bracelet for over forty years, and it is today their best-known product by far. The company began in 1855 as Benjamin Henry Britton and Sons at a workshop at 83 Vyse Steet, Birmingham, makers of "gold guard and fancy chains." These are more commonly known as pocket watch chains. By 1929, they had become B. H.  Britton & Sons, "manufacturers of Gold Cigarette Cases, Vesta Boxes, Tear-offs, Alberts, Platinum Alberts, Signet Rings, Expanding Watch Bracelets, Slave Bangles, Flexible Bracelets, Sleeve Links, Guards, Necklets in 9 ct., 15 ct., and 18 ct. and Silver Alberts." (A bit of explanation: an Albert chain is a type of heavy pocket watch chain, and a Vesta box is a match safe). The factory had also relocated to 35 Hockley Hill, Birmingham, in the middle of what was (and still is) known as Birmingham's Jewelry District. They also had opened their London sales office at New House.

Pocket Watch Chain made by B.H. Britton and Sons

B.H. Britton and Sons was an especially prolific maker of silver chains, and also made silver-cased cigarette lighters. It may have been this cigarette lighter connection that brought Dudley Howitt to the firm.

Sterling Silver Cigarette Lighter signed "B&S"

According to surviving Britton family members, the company also made gold watch cases for Rolex and exported watch chains world-wide. There is also evidence that Rolex sold some watches with Bonklip bracelets during the 1930's and 1940's.
1940's Rolex sold recently at Christie's with apparently original Bonklip 

While perhaps not the large-scale industrial operation that Krementz was, B.H.B. & S. were certainly the preeminent watch chain maker in England.

The Bonklip watch bracelet represented a move into mass-market products for the firm, which had been essentially a fine jewelery maker (far more so than Krementz, which was basically a costume jeweler). The Bonklip can, however, be found in solid 9 ct. gold, with London hallmarks and a "B & S" maker's mark. The vast majority of Bonklips, however, were stainless steel with some gold-filled as well.

9 kt solid gold Bonklip bracelet signed "B & S"

Even in the 1960's, B.H. Britton and Sons still considered themselves primarily goldsmiths, and had expanded into signet rings, gold crosses, and as a sign of changing fashions, tie clips. The firm, after 120 years of making fashionable accessories for gentlemen, as well as equipping RAF aircrews and countless military personnel, folded in about 1973. The fact that their factory was slated for demolition to make way for road improvements may have had something to do with it. The British Ministry of Defense officially dropped the Bonklip from their stock-lists about this time, replacing it with a nylon strap with a leather pad, and eventually the now famous "G-10 NATO" nylon strap.

B.H. Britton and Son's patent expired in 1950, and while it still remained a popular product, it faced growing competition from G & F (Gay Freres, later to be bought by Rolex) and other Swiss, French and American (Forstner) copycats. The Bonklip even faced competition from another Birmingham Jewelry company, Clewco (E.J. Clewley and Co.).

A few words about the Bonklip military connection. While the British Ministry of Defense only issued Bonklip bracelets to RAF aircrew in the 1950's and 1960's, it is wrong to say that the Bonklip bracelet is "incorrect" when worn on earlier military watches. Enough ATP (Army Trade Pattern), A.M. (Air Ministry) and post-war W.W.W. (wrist watch, waterproof) watches survive with period Bonklips to make it clear that this was a popular and useful watch bracelet that was widely adopted as a private purchase by thousands of soldiers throughout WWII and after. They even appear on U.S.A.A.F. A-11 watches, a big improvement over the pigskin and cheap cotton issue straps.

The Bonklip certainly out-sold the Krementz bracelet many times over, and represents a proud piece of Britain's manufacturing and military heritage.


  • The Jewelers' Circular-Weekly, Vol. 78, Issue 1 (February 5, 1919), pp. 193-195.
  • Board of Trade British Industries Fair Catalogue 1929: held at The White City, Shepherd's Bush, London W12, from 18 February to 1 March, 1929, and organised by the Department of Overseas Trade (Empire and Home Edition).

Thursday, November 17, 2011

Diving 101

Tom here, and I wanted to give a little background and tell a bit about my passion and hobby. Watches and SCUBA diving. Corvus is my company and I reserved for myself the Bradley Dive Watch serial number 32. I have mounted it recently on a Corvus Shell Cordovan watch strap, black with white stitching. Previously, I have used one of the first batch of “soft” Real Bond watchstraps.

My love of dive watches grew out of my serious SCUBA diving addiction. I am certified in open water, Nitrox and wreck penetration. I have over two hundred logged dives and many more I just forgot to write up. I use an Aeris xr2 dive computer/regulator with a US divers back up.

I have spent a gob of money traveling to many of the best dive sites on earth. I am not wealthy, just obsessed. I view money spent on dive equipment is the most important thing you can do. To blow 6 grand on a cool dive vacation and use Ebay purchased equipment is just stupid/dangerous. I have seen many sad cases where cheap equipment caused the diver to miss dives due to regulators blowing out, fin back strap breaking (at the point of getting in the water) and hypothermia from cheap or inadequate wet suits. The same goes for your ultimate backup – your dive watch.

About the dumbest thing I saw was this summer was when my dive trip "assigned" partner did not have a computer or much idea how the tables worked. She just went to 100 feet plus with a 100 cubic foot tank. She was really pushing the limits and did not understand what she was doing. I brought her up in a non-emergency ascent and she had no idea how close she had come to mandatory decompression, or the bends. She had been certified a long long time ago and had kind of BS'ed her way on the trip. Other than her lack of basic diving skills, she was very nice and appreciated my buddy coordination. More about this fantastic dive trip in a future blog post.

I guess I should tell some of my dumb ass moments. Several times I took my boat to Pentwater, Michigan, to dive its excellent wrecks. The best preserved is the Anna C. Minch, sunk during the Armistice day Storm of 1940. We found it by studying the wrecks location and all data we could assemble. Then we took off with GPS and fish finder humming along to aid us in finding Anna. At the exact location, just south of Pentwater and half a mile off Silver Lake Dunes state park, we found the wreck in about 30 feet of water. Not only did our GPS and fish finder locate her, perfectly, but several white Clorox bottles were tied over it to help divers find her!

Anyway, the surface water temp was in the 60's and bottom temp in the 40's. I was trying out a different wet suit, I was used to the weighting for a farmer john suit and was trying out a one piece style. I had about 45 pounds of lead on my hips and when I went to release the air in my BC I went into an uncontrolled descent. Just as quick as I tapped the exhaust button I went straight down. Fortunately the depth was only 30 feet, but I still suffered a nasty squeeze on my sinus. It hurt but I finished the dive and for the next week blew bloody snot globs. I consulted a non dive doctor and he said if the discharge turned green and smelly to come back to his office. It cleared up but I have been very careful since, to double check my weights for the different wet suits I use.

I guess the point of this blog is to stress the basics of diving, use the buddy system, have good equipment and know where you are going. After all my expensive equipment and experience, failures in training, planning and equipment can happen to everyone at any time.

My Corvus watch has never let me down. In multiple dives over one hundred feet it is the final backup to saving your life. I always set the bezel and know how long I have been under. It may be my third redundant back up, after my two computers, but it is the simplest and toughest! There are lots of great watches on the market, but my Corvus is the one I bet my life on.

Saturday, October 22, 2011

Introducing Our New Two-Piece Shell Cordovan Strap

We'll get right to the point. This is the best leather watchstrap available. Period. Here's why: It's extremely thin, very comfortable, waterproof, looks great when new and gets better with age, won't rot or start to smell like gym shoes, and it will last for years.

First, it is a single layer of leather. This is unheard of in quality watch straps. The reason is that all hide leather has a skin side and a suede side. While all hide leather absorbs moisture, the suede side sucks it up like a sponge. Therefore, all quality leather hide straps have to use a double-layer construction so that the suede side(s) are concealed. The best straps also have the raw edges folded over and tucked in before sewing or gluing. This is called the art manuel method of construction. All this folding, gluing, stitching is done by hand and adds cost, thickness, and lateral stiffness.

Even when an ordinary hide leather strap is made using these proper techniques, it will absorb sweat and eventually rot or smell. A famous German manufacturer of high-quality hide leather watchstraps recommends that you replace your leather strap every six months. This is realistic. Think about those leather moccasins that you wear without socks in the summer. Ick.


All of these problems go away with Shell Cordovan. Why? Because shell is not hide. It is a muscle that is located below the skin (hide) of horses, and only on their buttocks. (Yes, we've heard all the jokes!) Added to this, the Horween Company takes six months to tan the product by adding oils and waxes to enhance the natural waterproof nature of the shell. The result is miraculous. A waterproof, supple, and great-looking "leather" that is unlike anything else.

Shell Cordovan has traditionally been used for shoes, for obvious reasons. Shell Cordovan shoes and boots have been known to last for decades. When future general George S. Patton began to serve as an aide to General John Pershing during WWI, he immediately copied the General by ordering a pair of custom-made Shell Cordovan boots, a style he famously wore the rest of his life.


No! Only mature animals that have died of natural causes are used by the Horween Leather Company for their shells. While Shell Cordovan was once made by a number of leather tanneries in the USA, for many years, Horween has been the only remaining maker of Shell Cordovan. They have made it in the same way since 1905. No other tannery in the world makes genuine Shell Cordovan.

A word here about Japanese "Shell Cordovan." There have been persistent rumours that a Japanese tannery has recently begun to make "shell cordovan." Here is the real story. In Japan, horse meat is a food product. It is considered a delicacy and often eaten raw, like sushi. As a result, horsehide is a by-product of feedlot slaughterhouses. Shell Cordovan is hugely popular in Japan, especially for shoes, and rightly so. We sell a lot of our watchstraps in Japan. But Japanese-made "shell cordovan" is not the same product as our genuine Horween Shell Cordovan!

Horses are livestock in Japan. They are specially bred for food, slaughtered when young, and are raised under very different conditions than riding horses in the USA. The musculature in the horses hind-quarters never develops to anywhere near the extent of American horses. While these animals' hides make excellent reproduction WWII flight jackets, the shells cannot be used to product top-quality Shell Cordovan.

Beware of products that falsely claim to be made of Shell Cordovan. The word "Cordovan" is often used to describe a certain reddish-brown color of any kind of leather. (This color is available in our Horween Shell Cordovan as "Oxblood.") It does not by itself indicate Shell Cordovan. Unless you see the Horween Shell Cordovan Stamp on the back of the leather, it is NOT genuine Shell Cordovan.


Available in 18, 19 or 20 mm widths, with a slight taper. 19 and 20 mm tapers to 18 mm at the buckle end; the 18 mm tapers to 16 mm. The shell is so thin (less than 1 mm) that we cannot produce these two-piece straps in larger widths. (For watches with 22 and 24 mm lug widths, we recommend our Shell Cordovan NATO straps.) All genuine, and incomparable.

$115 with free Priority Mail Shipping world-wide.

Wednesday, September 28, 2011

Cordovan NATO on a Seadweller

We are delighted to share some wonderful photos taken by one of our customers (Thanks R.N.!!) of our 20mm Shell Cordovan NATO strap on his Rolex Sea Dweller. This is the natural with white stitching.  We emailed back and forth several times, discussing which strap would work best on this watch, and we must say that the results are as cool as it gets. The new Sea Dweller is really a serious tool and the Shell Cordovan is a great match.

Saturday, September 24, 2011

Our New Shell Cordvan Postcard!

We've just created a new oversized postcard that will be included with your Corvus order. Similar in concept to our popular Real Bond NATO postcard that is included in all Bond strap orders, this one documents the production of the Horween Shell Cordovan used in our leather NATO and Bund-style straps. Watch for our introduction of NEW styles of Shell Cordovan watchstraps in the next few weeks!
The strange code on the bottom right is called a "QRCode," and allows you to scan it with a smartphone like an Android or an iPhone and get a link to our website!

This text is from a Horween Tannery 1950's document. We couldn't have said it better ourselves!

Friday, September 23, 2011

New Corvus Products Review in Japanese

We were very pleased to learn that a popular movie Blog in Japan posted a detailed review of our products, focusing on our new Movie-Style Bond Strap and our King Kong Company Vietnam T-Shirt from theDeNiro movie, Taxi Driver. If you can read Kanji, please enjoy. Otherwise, it's worth a look for some great Blu-Ray screen captures from Thunderball and Goldfinger. Very otaku.

Japanese Movie Blog Corvus Review

Thursday, September 22, 2011

Really Vintage Military Diver

We found this photo of an antique cigarette card from the 1920's. I imagine that this is a fairly fanciful image, and I doubt that this diver needed a watch! (Although it looks like he might be wearing a small one on his left wrist!)

It is interesting to remember that until the 1950's, diving watches mostly used horsehide leather straps (for example, WWII Panerai watches). I am pretty sure they were Shell Cordovan, like our NATO straps. No other leather is even close to being as waterproof.

Friday, September 16, 2011

The Greatest Rolex That Never Was.

In April 2004, Antiquorum auctioned a strange watch. It was purported to be a Rolex prototype designed for the U.S. Military. Here is the catalog auction description:

This is the first watch known to be sold at auction, with dial marked "U.S.Marine". The case of this watch is perfectly engineered for heavy military use. Its large size ensures that the wrist will be completely covered, thereby preventing the injuries sometimes caused by violent impacts to smaller watches, the winding crown positioned at 4 o’clock, with its sloping crown guard, affords better protection than the standard configuration of crown and guard at 3. The rounded hoods covering the lugs reduce the possibility of the watch’s becoming caught in equipment and also act as locks for the bezel. The steel rotating 12-hour bezel effectively gives an hour and minute recorder which is invaluable in military exercises. Overall, this watch was designed for only one purpose, to tell time in some of the harshest environments and under the most extreme conditions, the types of activity that are synonymous with the U.S. Marine Corps. According to unofficial information from Rolex, two similar prototypes by Tudor were offered to the U.S. Navy. One of these Tudor prototypes was sold by Antiquorum NY in May 1998, lot 36. The present watch will be illustrated in the upcoming book on Rolex, soon to be published by Guido Mondani.

The sale of this watch caused a great deal of controversy. Some experts declared it an unequivocal fake. At first glance, it would seem to be a very fanciful creation. The citation to "unofficial information" and the laughable "U.S. Marine" (vs. U.S. Marines) inscription did not encourage much confidence either. Still, someone appears to have paid over $100,000 (114,000 Swiss francs) for this admittedly rare and unique object.

My own opinion is the same as what appears to be the consensus among advanced military watch collectors. Fake. Or is it? First, if this is a prototype U.S. Military watch, there would exist some documentation of a RFP or milspec that this watch would have been made to compete for. There is none. In addition, it would have been unprecedented that the Marines would have solicited a separate watch for their branch. Due to historical connections, the Dept. of the Navy's Bureau of Ships has always handled Marines procurement. In fact, the Tornek Rayville TR-900, although a Navy procurement, was ultimately issued to mostly (if not exclusively) Marine Recon personnel during the Vietnam war. We would be led to believe that this watch would have competed with the Benrus Type I. While the Benrus is well documented, no one has found a peep about any Rolex or Tudor competitor.

Finally, a well-regarded Hong Kong-based watch restorer took credit for this creation about four years ago. It was reported to be a fantasy piece put together with real Rolex parts and Vietnamese (some irony there) components, custom made for a wealthy Japanese collector to his specifications.

Real or not, the watch is a masterpiece of design. The Rolex Submariner is the most iconic watch design of the 20th Century. It has been knocked off and "homagde" to death. It is the watch design that has launched a thousand bastard children. Virtually none of these spawn have contributed anything new to this design idiom.

However, the best was yet to come. Enter Sato-san. "Ken" Sato invented the "homage" watch genre in the 1990's with his fanciful and parodic Rolex Submariner reinventions sold in Japan under the "Prolex" label, and then later, the "RXW" brand. (For a primer in Sato-san's work, see here .) These are not knock-offs or copies, and surely not "fakes." Ken Sato is an advanced collector of vintage Rolex watches who combines this with a deep love of the Rolex design vocabulary and a great eye for design.

After coming up with his uniquely Japanese take on the Milgauss, Comex, and Milsub, Ken Sato took on the design of the controversial U.S. Marine watch, calling his creation the "Subpromarine." I hope that he never believed that this U.S. Marine "prototype" was real. However, I am sure that he immediately recognized the beauty of the design. But, where the design of the Hong Kong fantasy piece was overblown, Ken Sato's take on it was subdued, and in so doing, achieved design perfection. To summarize, Ken Sato's watch was an homage to a fake, one that arguably surpassed the original. The ultimate irony was when Sato's Subpromarine began itself to be faked, and was being sold for 1/3 the price on Ebay. There was no comparison, however, the fake having a glass crystal, a cheap Chinese movement and a plastic retainer ring. A fake of a homage to a fake.

I have had my eye on this watch for some time. But when I saw that Ken Sato's Website showed that only a dozen were left in stock, at a clearance price, I couldn't resist.

The Corvus TimeSquare

We received this question through the website the other day:

I have a TimeSquare, Model:4000005 that has worked incredibly well for years, but the center two "lights" have stopped working. Can this be repaired? Thank you.

At first we thought it was spam, but then the gentleman sent the same message again and I realized what he might be getting at. A quick Google search later led to the following discovery, courtesy of something called Google Books:

We had previously learned about this "other Corvus" when a customer sent us a photo of a funky 1960's LED wristwatch made by them. It's good to know that the gentleman's Corvus TimeSquare gave him many years of good service. We are sure that our "new Corvus" timepieces will give equally good or better.

Sadly, we could not repair his TimeSquare for him.