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.