Luminor 2020 – Debunking Panerai’s Fictional History Of Tritium-Based Lume – Vintage Panerai and other iconic timepieces under the loupe at Perezcope

On May 8, 1951, the mightiest man-made explosion the world had ever seen –  unleashing the cataclysmic energy of 225 kilotons of TNT – shook the Enewetak Atoll in the course of the Pacific Ocean. Tiny quantities of tritium – which had price the US thousands and thousands of Dollars – have been answerable for boosting the blast to this extent.


George, the experimental gadget set off by the US as a part of Operation Greenhouse, was designed to validate the ideas of nuclear fusion required for the event of thermonuclear weapons. Based on a standard nuclear bomb, George had a small combination of liquified deuterium and tritium positioned at its core. Compressed by the large warmth generated within the first milliseconds of the blast, the atoms within the combination have been compelled to fuse with one another. As a outcome, a lot of high-energy neutrons have been launched rising nuclear fission (splitting of atoms) many occasions over. This was the primary time males had achieved nuclear fusion, the very course of that happens inside the solar.

The US was underneath nice stress. In September 1949, information broke of a successfull nuclear take a look at within the Soviet Union. Western intelligence analysts had not anticipated the Soviets to get a nuclear bomb earlier than 1953.

Soviet RDS-1 take a look at shot on August 29, 1949

In consequence, US President Harry S. Truman gave highest precedence to the pursuit of thermonuclear weapons as a way to keep forward of the sport.

Early calculations prompt that extraordinarily massive portions of deuterium and tritium, each heavy isotopes of hydrogen, can be required as thermonuclear gas. The greatest drawback the scientists at Los Alamos have been dealing with was, tritium was unobtainable on the time and this actual fact delayed the method significantly.

Tritium could possibly be produced in modified particle accelerators or heavy water-moderated reactors. To maintain the manufacturing of tritium strictly army, US President Harry S. Truman ordered the development of 5 specifically designed heavy water-moderated nuclear reactors close to the Savannah River, 25 miles (40 km) southeast of Augusta, Georgia, to provide the desperately wanted tritium.

R Reactor development on the Savannah River Plant

Built with the specter of a nuclear assault in thoughts, the US authorities seized 310 sq. miles (800 km2) of land and distributed the reactors randomly over the whole space with a distance of at the least 2.5 miles to one another.


Two massive synthetic lakes have been created to supply sufficient coolant for the reactors. The small city of Ellenton and round 6000 residents residing within the space needed to be relocated.


The Savannah River Plant produced a lot of the western world’s tritium provide from 1955 till 1988, when the power was shut down for security causes. Tritium manufacturing was relaunched in 2007.

Construction of the Savannah River Plant started in 1951. Until the primary reactor (R Reactor) went vital in 1953, the tritium wanted for Operation Greenhouse was produced on the Hanford Site within the state of Washington. The Hanford reactors had produced the plutonium-239 utilized in Fat Man, the atomic bomb dropped on the Japanese metropolis of Nagasaki.

B Reactor on the Hanford Site, the primary large-scale nuclear reactor ever constructed

To produce tritium, the Hanford reactors needed to bear a lot of modifications and manufacturing of plutonium got here to a halt. The price for rifitting the reactors was between USD 2 million and USD 5 million (USD 20 to 50 million right now). By mid 1950, Hanford was prepared to provide round 10 grams of tritium per yr.

The manufacturing of tritium is an advanced course of that requires huge investments and huge infrastructure which in these days may solely be supplied by massive industrial powers such because the US and the Soviet Union.

According to the trendy Panerai firm, G. Panerai e Figlio patented a tritium-based luminous compound named Luminor in January 1949.

Where did the tritium for Luminor come from? Giuseppe Panerai didn’t have a nuclear plant in his basement, nor a particle accelerator. As a matter of reality, the primary Italian particle accelerator AdA (Anello Di Accumulazione) was inbuilt 1961. The first Italian nuclear reactors have been accomplished by 1964 with the assistance of the American corporations Westinghouse and General Electric.

How is it potential that Giuseppe Panerai – the proprietor of a modest mechanical precision workshop – had sufficient tritium at his disposal to experiment and create a tritium-based luminous compound whereas probably the most highly effective nation on Earth was struggling to provide even smallest quantities of tritium?

G. Panerai e Figlio workshop within the early Forties

The reply is easy. The story put forth by the trendy Panerai firm is pure fiction. G. Panerai e Figlio did NOT invent a tritium-based luminous compound in 1949. They merely registered the trademark Luminor which had nothing to do with tritium. The trademark Luminor remained in a drawer till round 1965, when Mr. Panerai created his personal combination following the introduction of tritium-activated compounds within the Swiss watch trade.

Panerai’s self-luminous compounds

Luminor, and earlier Radiomir, have been self-luminous mixtures utilized by G. Panerai e Figlio over the course of time to light up all kinds of dials, calculating gadgets and different devices.



Radiomir was a radioluminescent combination which used radium-226 as an power supply to excite zinc sulfide (inorganic phosphor). Zinc sulfide emits gentle upon excitation by radiation. If uncovered to solar or synthetic gentle, it can glow for a brief time frame.


Contrary to well-liked perception, Radiomir was by no means patented. Radium-based luminous mixtures have been invented and patented by Dr. George F. Kunz (789811 and 789812) in 1903.

Link to patent: Luminous Composition

What Guido Panerai patented in 1915 have been sights illuminated by radium-226/zinc sulfide powder enclosed in small, hermetically sealed vessels which made it potential to goal at targets at the hours of darkness. The title Radiomir is a mixture of Radio (radium) and Mire (sights).

What Guido Panerai invented was mainly this.


The image beneath is an excerpt from Guido Panerai’s British patent software from August 1915.


Improvements in Sighting-devices for Firearms and Torpedo Tubes

This invention pertains to sighting gadgets of the type that are rendered luminous by way of radium and has for its object to supply improved means for rendering such sighting gadgets luminous, the mentioned gadgets being for the use in small arms, machine weapons, ordnance and torpedo tubes in order that these weapons could be fired at evening with a better diploma of accuracy than heretofore.

Link to patent: Improvements in Sighting-devices for Firearms and Torpedo Tubes

Panerai’s RadioMire (radium sights), particularly the torpedo aiming calculators, have been well-known within the Italian Navy. The title Radiomir turned quickly synonymous for Panerai’s radioluminescence.


Radium-226 is a extremely radioactive isotop with a half-life of 1,600 years. In addition to alpha and beta rays, radium-226 emits additionally penetrating gamma rays which might cross via the human pores and skin. When ingested or inhaled, radium is handled by the physique as calcium and deposited within the bones (so-called bone seeker).

The world turned conscious of the hazards of radium-226 following a sequence of lawsuits towards the American firm US Radium Corporation within the late Nineteen Twenties. Female manufacturing facility employees answerable for portray the dials have been instructed to lip-pointing the comb as a way to paint with extra accuracy. The penalties of ingesting radium-226 have been catastrophic and a lot of the Radium Girls died a painful loss of life. After this debacle, the circumstances for employees have been improved and particular security measures enforced.


Giuseppe Panerai was effectively conscious of the hazards posed by radium-226. The radioactive combination was subsequently sealed deep contained in the dial behind a thick layer of hardened resin (plexi).


The image beneath reveals the inside layer of a typical Radiomir dial from WW2. The harm attributable to the radioactive materials is clearly seen.


Besides the hazards associated to radiation, radium-226-activated luminous compounds had one other massive drawback. The luminosity diminished pretty rapidly as a result of destruction of the zinc sulfide by the ionizing particles emitted by radium-226. Watch dials of this sort misplaced their luminosity utterly after solely three to 5 years. Radiomir dials had to get replaced periodically.

Ref. 3646 watches that remained in service after WW2 have been up to date with trendy Nineteen Fifties Radiomir dials in some unspecified time in the future. The subsequent image reveals Vice Admiral Ernesto Notari’s 3646 which is exhibited on the Navy Museum in La Spezia.


This watch is an ideal instance for a timepiece that remained in service after the battle. The unique dial misplaced its luminosity and was changed with a typical Nineteen Fifties Radiomir dial.

During WW2, Notari was a SLC (Maiale) pilot. When Italy formally surrendered to the Allies in September 1943, Notari remained loyal to the King of Italy and enrolled with the Allies within the south to struggle towards the Nazis. After the battle, Notari was assigned twice as commander of the newly shaped assault models and reached the rank of Vice Admiral.


Luminor, then again, was a contemporary compound with radioactive tritium because the power supply to incite zinc sulfide to glow. Compared to radium-226, tritium is kind of innocent, so long as it’s not ingested or inhaled. The half-life of tritium is barely 12.3 years. The low power beta rays emitted by tritium can not penetrate the pores and skin.


Tritium, also called hydrogen-3 (3H) is an isotope of hydrogen, a variant with equivalent chemical behaviour. More on this later.

In right now’s Panerai mannequin taxonomy, the title Radiomir is used to confer with watches with Rolex-style screw-down crown whereas Luminor is the title given to fashions that includes the enduring Panerai crown-protecting gadget.


This is an excessive oversimplification which has no foundation in actuality and disregards the true historical past of G. Panerai e Figlio. Here is why.

The first 6152/1 fashions with patented Panerai crown guard have been equipped to the Marina Militare with Radiomir dials, as could be seen within the image beneath from G. Panerai e Figlio’s picture archive. In the trendy Panerai’s e book, it is a Luminor however clearly, it incorporates a Radiomir dial as an alternative.


Here is one other picture from G. Panerai e Figlio’s picture archive. Depicted is a so-called Destro the place the crown guard is on the left facet of the case. This watch incorporates a Radiomir dial as effectively.


Only a handful examples of Ref. 6152/1 that includes the well-known crown-protecting gadget that retained the unique Radiomir dials have survived. Most of those watches have been up to date with Luminor dials in some unspecified time in the future in time.


The luminosity in radium-226-based dials had a lifespan of solely three to 5 years as a result of deterioration of the zinc sulfide. Since these dials had to get replaced periodically, probably the most believable rationalization for the existence of watches that retained the unique Radiomir dials is, they have been unlawfully taken out of service in some unspecified time in the future (stolen).

Reference 6152/1 was produced by Rolex in 1955 and later personalized by Panerai. To set up the half-moon formed crown guard on Ref. 6152/1 circumstances, Panerai machined the circumstances to create two flat seats on the rounded case, as pictured beneath.


The unique screw-down crown was changed with a spring-loaded crown.

Giuseppe Panerai filed the Italian patent software for the enduring crown-protecting gadget on November 30, 1955. Claims the crown guard was developed a lot earlier throughout WW2 are unsubstantiated.

Link to patent: Fluid-tight winding means for a keyless watch

The image beneath reveals a 6152/1 with case quantity 124777 that includes the Panerai crown guard. 124777 is a typical Rolex Oyster case quantity from 1955.

Rolex-made 6152-1 with added Panerai crown-protecting gadget (Photo: Luciano Cipullo)

Rolex produced a complete of round 500 items of Ref. 6152/1 with case numbers starting from round 124495 to 124999.

The Luminor “Patent”

According to the present Panerai – an organization created by Richemont from scratch after buying the rights for the title Officine Panerai in 1997 – Radiomir was changed by Luminor in 1949. The following screenshot was taken from the historical past part of the present Panerai web site.


A brand new self-luminous substance, Luminor, supersedes the radium-based paste. Tritium (hydrogen isotope) based mostly, this compound is protected by the patent filed on 11 January 1949 underneath the “Luminor” trademark. Officine Panerai attracts inspiration from the title of its newly patented substance for its different historic mannequin that follows the Radiomir watch – the Luminor.

Link: History of Panerai (

To again this declare, the trendy Panerai firm refers to a “patent” filed on January 1949 however reality is, the talked about doc is NOT a patent for an invention however merely a trademark registration for the title Luminor.


Brevetto per Marchio d’Impresa is Italian for Registered Trademark. Products associated to the title Luminor are listed as the next:

Merci e prodotti da contraddistinguere: prodotti sotto qualisiasi forma (solido, pasta, polvere, liquido) luminescenti, fluorescenti, forforescenti e simili (classe 49).

Translation: Goods and merchandise to be distinguished: merchandise in any type (strong, paste, powder, liquid) luminescent, fluorescents, phosphorescent and the like.

There is completely no mentioning of tritium or how the compound is made on this doc. Let’s return to Panerai’s declare:

Tritium (hydrogen isotope) based mostly, this compound is protected by the patent filed on 11 January 1949 underneath the “Luminor” trademark.

The referenced doc doesn’t defend a selected compound as claimed by Richemont. It is only a trademark registration for merchandise associated to sure luminous compounds generally.

On web page 17 of the present 2018 – 2019 catalogue, Panerai makes an identical declare:

In 1949 Officine Panerai patented a brand new self-luminous substance based mostly on Tritium (an isotope of hydrogen). This compound was protected by a patent registered on eleventh January 1949 underneath the title “Luminor”.

In a press release made on web page 53 of the present 2018 – 2019 catalogue, Panerai goes one step additional and claims Officine Panerai truly invented tritium-based luminous compounds, implying additionally they invented radium-based compounds:

The Radium-based substance initially used to make the dials completely seen in circumstances of absolute darkness was progressively changed by a brand new self-luminous substance based mostly on tritium (an isotope of hydrogen) additionally invented by Officine Panerai: this was “Luminor”, a substance protected by a trademark registered on eleventh January 1949 for “merchandise luminous in any type, fluorescent, phosphorescent and related” intented significantly for army use.

A better take a look at the products and merchandise listed within the trademark registration associated to Luminor reveals one more essential element. Tritium is radioactive. A tritium-based compound is radioluminescent as per definition however this adjective is nowhere to be discovered within the trademark registration.

Goods and merchandise to be distinguished: merchandise in any type (strong, paste, powder, liquid) luminescent, fluorescents, phosphorescent and the like.

If the trademark registration was supposed for a radioactive compound, radioluminescent can be the very first thing to be talked about.

Furthermore, if Luminor was already out there in 1949, why do all references from the Nineteen Fifties nonetheless have Radiomir dials, specifically Ref. 6152 from 1953, Ref. 6154 from 1954, Ref. 6152/1 with Rolex screw-down crown from 1955 and the big GPF 2/56 from 1956 made for the Egyptian Navy?

The subsequent image reveals Admiral Amedeo Vesco’s Rolex-made 6152 from 1953 with Oyster case quantity 956638. All identified examples of Ref. 6152 have Radiomir dials.


Rolex-made Ref. 6154 from 1954 with case quantity 9975XX. There are round 20 identified items of Ref. 6154 and all of them function Radiomir dials.


The subsequent image reveals a Ref. 6152/1 with case quantity 124547 made by Rolex in 1955. Ref. 6152/1 has decrease case numbers than Ref. 6152 and Ref. 6154 as a result of Rolex began from zero once they reached 1 million in 1954.

This very watch was on the wrist of an Italian Navy diver when he died throughout an underwater train off the coast of Sicily in 1957. The dial of this watch cleary says Radiomir.


The following Ref. 6152/1 watch was offered at Sotheby’s in October 2019. It was bought from Panerai in 1958 and nonetheless featured a Radiomir dial.


This timepiece is accompanied by a letter from the Centro Subacqueo ed Incursori “Teseo Tesei” (precursor of ComSubIn) stating that Lieutenant Giuseppe Rasenti acquired the watch from Panerai in March 1958.



Si dichiara che il Tenente di Porto Sig. Giuseppe RASENTI ha regolarmente acquistato dalla Ditta PANERAI di Firenze un orologio subacqueo “PANERAI”.

La Spezia, 10 marzo 1958

Translation: DECLARATION: We declare that Lieutenant Mr. Giuseppe RASENTI has frequently bought from the corporate PANERAI in Florence a “PANERAI” diving watch. La Spezia, March 10, 1958

The GPF 2/56, Panerai’s first personal timepiece created with none involvement from Rolex, was produced for the Egyptian Navy from mid 1956 onwards. All watches present in Egypt have been geared up with Radiomir dials.


The sample could be very clear. Throughout the Nineteen Fifties, G. Panerai e Figlio continued to make use of Radiomir dials. In latest years, the trendy Panerai firm promoted the fictional narrative that the references 6152, 6154 and 6152/1 with conventional hornlugs and screw-down crown have been so-called Radiomir 1940 fashions, produced within the Forties. The Rolex Oyster case numbers of those fashions nonetheless, bear witness that each one of them have been produced within the Nineteen Fifties.


Certain fashions with tradional hornlugs and screw-down crown have been discovered with Luminor or Marina Militare dials. Dials that includes Marina Militare engravings have been made with tritium-based Luminor as effectively, aside from a bunch of altered Kampfschwimmer dials from WW2 with faux Marina Militare engravings which have been manipulated by Rinaldi and co.


The rationalization for the existence of Luminor dials in Ref. 6152/1 watches with out crown-protecting gadget is fairly easy. In these circumstances, the unique Radiomir dials have been changed with trendy Luminor dials in some unspecified time in the future after 1965. As talked about, the luminosity of Radiomir dials lasted solely three to 5 years and the dials had to get replaced periodically.


To recapitulate, in 1949, tritium was NOT out there, anyplace on planet Earth. After WW2, tritium was considered an essential part for thermonuclear weapons and the Americans have been struggling to develop such weapons as a result of unavailability of tritium. It is bodily unimaginable that Giuseppe Panerai had tritium in 1949.

Here is what actually occurred. Giuseppe Panerai got here up with a cool title for a future product and had it registered. Simple as that. In the identical breath, he additionally registered product names like Translux and Elux, all associated to luminous compounds generally.

What is Tritium?

Tritium is a gasoline. It is an isotope of hydrogen, which is probably the most fundamental component on Earth. Isotopes are variants of a chemical component which differ within the variety of neutrons in every atom. With just one proton, a hydrogen atom has the only nucleus identified and is subsequently the primary component within the periodic desk.

Hydrogen exists in two different isotopic types with equivalent chemical behaviour as hydrogen itself. Deuterium or hydrogen-2 (2H), which has a neutron along with the proton and tritium or hydrogen-3 (3H), which has two neutrons and one proton.

With two neutrons and one proton, tritium is the unstable isotope of hydrogen, thus radioactive with a half-life of 12.3 years. Tritum decays into helium-3 (3HE) with a yearly charge of 5%. Unstable isotopes have the tendency of changing into steady isotopes by releasing energetic particles within the course of. The particles emitted is what causes radioactivity.

Hydrogen is certainly one of two elements of water. Water molecules (H2O) encompass two hydrogen (H) atoms and one oxygen (O) atom. By changing hydrogen with deuterium, water turns into so-called heavy water (D2O). Since every of the 2 hydrogen atoms has an additional neutron in its nucleus, heavy water is heavier than regular water. Accordingly, ice cubes manufactured from heavy water sink in regular water. Heavy water is used as a moderator in nuclear reactors with unenriched uranium (uranium-238) to decelerate neutrons and break up uranium atoms extra effectively. Since unenriched uranium is less complicated to get, heavy water in massive portions is topic to authorities management in a number of nations.

Hydrogen atoms in water molecules will also be changed with tritium. This kind of water is known as super-heavy-water or tritiated water (T2O) and is in fact radioactive.

The title tritium is derived from the Greek phrase tritos, which suggests the third.

Production History Of Tritium

Tritium or hydrogen-3 is extraordinarily uncommon on Earth. The ambiance has solely hint quantities which happen via interplay of cosmic rays with the Earth’s atmospheric gases.

Hydrogen-3 was first detected within the mid Thirties by Lord Ernest Rutherford, Mark Oliphant and Paul Harteck from the Cavendish Laboratory on the University of Cambridge after bombarding compounds containing deuterium with deuterons (nuclei of deuterium/hydrogen-2) in a particle accelerator.

Rutherford requested the Norwegian Norsk Hydro heavy water plant (Vemork hydroelectric energy plant) to try to create tritium by electrolytic course of however after processing greater than 13,000 tons of heavy water, no tritium was discovered.


During WW2, the Norsk Hydro heavy water plant was sabotaged by the Allies to forestall the Nazis from growing nuclear weapons.

In 1939, utilizing Ernest Lawrence’s cyclotron on the Radiation Laboratory of the Physics Department of the University of California at Berkeley, Luis Alvarez and graduate scholar Robert Cornog fired heavy water molecules at deuterium and found that hydrogen-3 was radioactive.


Lawrence, the top of Berkeley’s radiation library, acknowledged the potential significance of this discovering:

Radioactively labeled hydrogen opens up a tremendously extensive and fruitful subject of investigation in all biology and chemistry.

Earlier in 1938, the German chemists Otto Hahn and Fritz Strassmann had succeeded in splitting an uranium atom. The strategy of splitting atoms turned often called nuclear fission. Fears the Germans may weaponize this discovery led a bunch of Hungarian scientists – supported by Albert Einstein – to warn the US authorities Germany could possibly be engaged on a nuclear bomb, a weapon with the damaging energy the likes of which the world had by no means seen earlier than.

The US authorities quickly realized the menace nuclear weapons may pose and created the Manhattan Project, a large analysis program during which one of the best scientists from everywhere in the world got here collectively to develop a nuclear bomb earlier than the Germans.

Uranium enrichment web site in Oak Ridge, Tenessee

Early within the Manhattan Project, the Italian-American physicist Enrico Fermi talked about to his Hungarian-American colleague Edward Teller that the temperatures developed by a fission bomb may presumably provoke nuclear fusion, the exact same course of that happens inside the solar. Teller instantly realized the potential for a nuclear tremendous bomb.

Edward Teller (left) and Enrico Fermi in 1951

There have been fears a thermonuclear explosion may ignite the Earth’s ambiance however these considerations have been dominated out by cautious calculations. Obsessed with the thought, Teller envisioned two ideas, the Classical Super and the Alarm Clock however the management of this system remained focussed on fission weapons.

The Manhattan Project succeeded in its process and on August 6 and 9, 1945, the US dropped the primary nuclear fission bombs on the Japanese industrial cities of Hiroshima and Nagasaki.


After the battle, Edward Teller remained hooked on the thought of making the so-called Classical Super, with a main fission stage igniting a secondary fusion stage. This idea required extraordinarily massive portions of deuterium and tritium which might act as thermonuclear gas. Under excessive warmth and stress, deuterium and tritium atoms can be compelled to fuse and unleash the brutal drive of the solar.

However, the developement failed to achieve traction as a result of tritium was unobtainable, even smallest quantities. Two options to unravel the tritium bottleneck have been mentioned. The development of specifically designed reactors and the modification of Lawrence’s cyclotrons in Berkeley. Any means that tritium could possibly be produced can be exorbitantly costly.

In September 3, 1949, a B-29 Superfortress operated by the Air Force’s climate service carrying particular filters designed to select up radiological particles, detected radioactive traces on a routine flight from Japan to Alaska. It quickly turned evident the Soviets had detonated their first atomic bomb.


Analysts had not anticipated a Soviet bomb earlier than 1953. An in depth espionage ring withing the Manhattan Project had supplied the Soviets with detailed info of the American bombs.

As a results of the Soviet take a look at, US President Harry Truman prioritized the pursuit of thermonuclear weapons. He ordered the development of 5 specifically designed heavy-water moderated nuclear reactors the place the large quantities of tritium calculated for the Classical Super can be shaped by neutron bombardment of deuterium. In the meantime, small quantities of tritium to check the ideas of nuclear fusion have been produced on the Hanford Site which needed to bear in depth refitting to take action. 

Beginning April 1951, on the distant Enewetak Atoll in the course of the Pacific Ocean, the US performed Operation Greenhouse, a sequence of checks that may result in the primary thermonuclear shot. The image beneath reveals VIP spectators witnessing the detonantion of the Dog gadget, a standard fission bomb with a excessive yield of 81 kilotons of TNT.


On May 8, 1951, the feasibilty of nuclear fusion was confirmed when the George gadget exploded with a yield of record-breaking 225 kilotons of TNT. George had a liquified deuterium-tritium combination at its core. When the atoms fused, numerous free neutrons have been launched which helped enhance the effectivity of nuclear fission many occasions over.

A couple of days afterward May 24, 1953, the so-called Booster, a compact gadget named Item with significantly much less fission gas than George was set off. Small quantities of deuterium and tritium injected as gasoline into the a cavity on the middle of the fission gas almost doubled the effectivity of the nuclear fission response as a result of launch of a lot of high-energy neutrons.


Teller and his fellow scientists quickly realized lithium deuteride would breed tritium by itself underneath the acute warmth and stress of the first stage. Prefabricated tritium was not required as gas for the secondary stage. This discovery led rapidly to a possible two-stage idea often called Teller–Ulam design.

a) fission main stage, b) fusion secondary stage, 1. High-explosive lenses, 2. Uranium-238 (“tamper”) lined with beryllium reflector, 3. Vaccum, 4. Tritium “increase” gasoline, 5. Radiation channel crammed with Polystyrene foam, 6. Uranium, 7. Lithium6- deuteride (fusion gas), 8. Plutonium, 9. Radiation case (confines thermal X-rays by reflection)

On November 1, 1952, the US examined the primary full-scale thermonuclear gadget. Weighing 82 tons, the gadget named Mike was not a deliverable weapon and resembled extra a laboratory than a bomb.


Mike’s thermonuclear gas consisted of liquid deuterium which needed to be saved in cryogenic state to keep away from evaporation. The main aim was to create the primary multi megaton-explosion. The power launched was solely restricted by the quantity of liquid deuterium.

The outcome was a ten.4 megaton explosion (10.4 million tons of TNT). Mike’s blast was so highly effective, the island on which the gadget was detonated was utterly vaporized, abandoning a crater with a diameter of 1.9 km (6,000 ft) and a depth of fifty m (164 ft). Compared to the Hiroshima bomb, Mike was 650 occasions extra powerfull.


Tritium remained nonetheless a vital part to spice up the first fission stage of thermonuclear weapons which finally led to an excessive miniaturization of warheads, sufficiently small to be deliverable by intercontinental ballistic missiles.


A contemporary Trident 2 submarine-launched ballistic missile can carry as much as eight W88 thermonuclear warheads, every with an estimated yield of 475 kilotons and independently targetable.


Since tritium decays into helium-3 with a half-life of 12.3 years, amassed helium-3 must be eliminated periodically whereas on the identical time, tritium gasoline is replenished.

The US invested massively into manufacturing services for big portions of tritium. Since tritium was not wanted within the quantities as beforehand calculated, the US Atomic Energy Commission (AEC) turned actively engaged in an isotope change information program and made tritium out there to licensed events.

New functions, particularly within the space of biomedicine, have been quickly discovered. The beta particles emitted by tritium are of low power and thus their penetrating vary in matter could be very quick. This made tritium a perfect tracer to discover the mechanism of chemical reactions by tracing the trail that the radioisotope follows inside cells and tissues.

The first patent for tritium-based luminous compounds

It was within the above talked about isotope change information program that tritium was discovered to be a perfect power supply for self-luminous compounds for watch dials and patented by Edward Shapiro on Oct. 29 1953 within the US.

The image beneath reveals an excerpt of mentioned patent.


Tritium is especially appropriate as a radiation supply for thrilling the phosphor due to its availability at comparatively low price (at present 10 cents/mc.), and the extraordinarily low penetrating energy of the beta radiation therefrom. The latter function permits using the tritium with a minimal of defending for the secure dealing with thereof, thus rendering it significantly helpful in functions the place personnel are prone to be in shut contact therewith.

Download patent: US 274951 – Source of Luminosity

This patent mentions the price of tritium in 1953. The worth was 10 cents per microcurie. In 1953, the quantity of tritium wanted for a mid Sixties Rolex Submariner dial with a most exercise of 25,000 microcurie (Swiss – T <25) would have been USD 2,500. To evaluate, in 1954, the primary Rolex Submariner was round USD 150. The tritium alone was 16 occasions the associated fee. The excessive worth for tritium was in all probability the rationale why watch corporations weren’t initially.

The existence of this patent places all claims to relaxation that tritium-based luminous compounds have been invented by G. Panerai e Figlio. This doc can be an important instance on how patents are presupposed to look. The compound and its manufacturing are described intimately over three pages.

There is an earlier patent filed in May 1946 within the United Kingdom mentioning tritium gasoline as an power supply to excite a fluorenscent materials. This patent nonetheless, doesn’t refer to look at dials. It was filed by a Hungarian firm named Egyesult Izzolampa es Villamossagi (United Incandescent And Electrical) situated in Budapest. It could be assumed the thought was leaked from Los Alamos by one of many many Hungarian scientists working on the secret US facility. There isn’t any means Hungary had tritium on the time.

Read extra: GB646414 – mprovements in and referring to fluorescent luminous our bodies

According to info discovered on the web site of RC Tritec Ltd., the Swiss firm that produces Swiss Super-LumiNova, they began growing tritium-activated self-luminous compounds within the late Nineteen Fifties.

Realizing the danger of radium, we began within the late fifties to develop a brand new self-luminous compound which was activated by Tritium to exchange Radium utterly. With its very low radiotoxicity and leaving no direct radiation outdoors of the watch, Tritium luminous compound was thought-about to be an ideal different.

Link: RC Tritec – Introduction and historical past

The Strontium-90 Debacle

The Swiss watch trade launched tritium-based lume following a lot of lawsuits towards Rolex within the United States of America. In 1959, the United States Atomic Energy Commission (AEC) discovered strontium-90 (90Sr) in Rolex 6542 GMT bezels. Strontium-90 is a radioactive isotope produced by nuclear fission with a half-life of 28.8 years. It emits virtually completely beta rays. Since strontium-90 is a typical fallout product of nuclear explosions, its use is strongly regulated by the Atomic Energy Commission.


Following this discovery, a number of American prospects sued Rolex for exposing them to harmful radiation. The Atomic Energy Commission had not licensed using strontium-90 in watches or clocks. and curiously, the AEC didn’t surveil using radium-226.


Rolex labored intently with the AEC to recall all 605 GMTs imported to the US and changed the bezels. By the tip of 1959 round 250 GMTs had been returned to Rolex. About three-fourths of them contained strontium-90.

Strontium-90 had just a few benefits over Radium. It supplied a better number of luminescent colors and the gradual lower in luminous depth was minimal for the reason that beta particles emitted by strontium-90 did much less harm to the zinc sulfide crystals. In addition, with 28.8 years, strontium-90 has a a lot shorter half-life than radium-226 with 1,600 years.

Following this debacle and mounting considerations among the many inhabitants, Rolex stopped utilizing strontium-90 and gradualy lowered the quantity of radium-226 in dials till a viable alternative was present in tritium.

The subsequent picture reveals the dial of a Rolex Submariner Ref. 5512 from round 1961. The phrase SWISS refers to using radium-226 within the luminous compound. The luminous dot beneath the 6 o’clock hour marker is outwardly a sign for a lowered quantity of radium-226. This kind of dial is known as Exclamation Mark dial.


In an ordinance from April 19, 1963 often called the Radiological Protection Act (814.50, Verordnung vom 19. April 1963 über den Strahlenschutz), the Swiss authorities banned using Radium within the Swiss watch trade. With the approaching into drive in 1964, working with radium-226 required a particular allow, its use needed to be justified and was topic to the management of the authorities. The act imposed radiation limits and radioactive substances resembling tritium (hydrogen-3) needed to be specified on the dials (T SWISS T). Special-purpose watches, such a diving watches, have been allowed larger ranges of radiation (SWISS – T <25 = exercise decrease than 25 millicurie or 25,000 microcurie).

The picture beneath reveals a 1965 Rolex Submariner Ref. 5512 dial with tritium-based luminous compound emitting lower than 25 millicurie, correctly declared.


The British Ministry of Defense (MOD) established new requirements for his or her timepieces. The kind of luminous compound needed to be indicated on the dials with a capital letter inside a circle. The image beneath reveals an Omega Seamaster 300 from 1967 that includes a dial with tritium-activated lume (T) particularly made for the Royal Navy.


Brands like Seiko or Blancpain (Tornek-Rayville TR-900) experimented with promethium-147, a radioactive isotope with a half-life of two.6 years which emits low-energy beta rays however because of its quick life span, the thought was not appropriate for the mass market.

Tornek Rayville TR-900

Ultimately, the Swiss watch trade went with tritium-activated compounds and sticked to them for nearly forthy years.

In 1998, Rolex began utilizing a brand new non-radioactive substance named Luminova developed by the Japanese firm Nemoto & Co. in 1993. Luminova is a photoluminescent or afterglow based mostly on strontium-aluminate. After being activated by daylight or synthetic gentle, the substance glows at the hours of darkness for hours. And that is the place it will get attention-grabbing.


G. Panerai e Figlio created a photoluminescent compound named Translux earlier than 1972. The flask pictured beneath was discovered within the basement of the Villino Panerai (Panerai Mansion) in Florence and has a G. Panerai e Figlio label on it. After Mr. Panerai’s loss of life in 1972, the corporate was renamed in Offcine Panerai, so that is clearly from earlier than 1972.


The product description said on the Translux label resembles that of Luminova:

Pigmento luminescente cioè ritrasmittente di luminosità – per un breve periodo di tempo – se preventivamente esposto alla luce naturale od artificiale. NON AUTOLUMINOSO

Translation: Luminescent pigment subsequently emitting luminosity – for a brief time frame – if beforehand uncovered to pure or synthetic gentle. NOT SELF-LUMINOUS

If G. Panerai e Figlio developed Luminova-style pigments earlier than 1972 – greater than twenty years earlier than the Japanese – that may be completely groundbreaking. It is attention-grabbing to see the trendy Panerai firm placing a lot effort into perpetuating fictional narratives in regards to the invention of tritium-based compounds when as a matter of reality they may have this wonderful invention of their portfolio.

Translux was used for luminous discs put in on ships and submarines as emergency lights.


Panerai’s watch store Orologeria Svizzera on the Piazza San Giovanni in Florence was a Rolex, Vacheron & Constantin and Longines retailer. When the Swiss watch trade switched to tritium-based luminous compounds round 1963/64, Giuseppe Panerai was one of many first to note.


Radioactivity points have been quickly mentioned in Italy as effectively. In a decree from February 13, 1964 (D.P.R. 185) issued to guard employees and the remainder of the inhabitants from harmful ionizing radiation, the Italian authorities banned sure functions and established exercise limits for watch dials. Interestingly, the Italian authorities continued to permit radium-226 if the exercise was inside sure limits. Regular watches have been restricted to 0.0002 millicuries whereas particular function watches resembling diver watches have been allowed as much as 0.0015 millicuries.

To evaluate, a WW2 Radiomir dial has an exercise of 0.0013 millicuries measured via the crystal of the watch. For Panerai and the Marina Militare there was no must react as Radiomir dials remained completely authorized.

D.R.P 185 got here into drive in mid 1964. It could be assumed that even when Radiomir dials had a better radioactivity than allowed, the Italian armed forces had to not comply instantly with the brand new regulation. Self-luminous dials with radium-226 weren’t solely utilized in watches but in addition in every kind of different army devices like compasses, depth gauges, plane devices, and many others. Replacing all these functions was a galactic effort.

The exact same limitations for radium-226 in watch dials have been ratified in a ministerial decree from July 14, 1970.

The indicators nonetheless have been clear. The world was transferring away from harmful radioactive compounds and it was solely a matter of time till radium-226 would even be banned in Italy.

Competition For Panerai

Around the identical time, the Marina Militare began shopping for state-of-the-art Eterna Super KonTiki diving watches with automated actions and time-recording rotating bezels. Panerai watches had turn out to be hopelessly outdated.

The Eterna Super KonTiki Ref. 130PTX within the image beneath is certainly one of six diving watches that surfaced in La Spezia in 2017. All watches bear particular markings on the casebacks and have case numbers which can be inside 27 numbers, making clear they belong to a particular batch produced for the Marina Militare.


These watches have been extra versatile than so-called Panerai watches as they may be used to time dives on compressed air versus learn time solely. The dials had massive tritium-based luminous plots and have been completely luminous even in darkest situation.

Interestingly, an Eterna Super KonTiki or related could be seen on the wrist of an Italian Navy diver on a photograph printed in an Officine Panerai SpA firm brochure from the Nineties.


In the mid Sixties, Panerai was sitting on tons of of outdated Ref. 6152/1 watches and confronted with a giant loss, they needed to give you an concept on tips on how to maintain these watches related to the Italian Navy.

To be capable of compete with trendy automated actions, Panerai determined to exchange the unique low energy reserve Cortebert 618 calibers (36 hours) with Angelus 240 8-days actions.

Panerai had used these calibers for the primary time in 1956 to energy the big GPF 2/56 (2/56 = 2nd mission 1956) made for the Egyptian Navy. The Angelus 240 caliber was developed within the mid Thirties by Stolz Frères in Switzerland as a motion for desk and alarm clocks.


For Panerai, Stolz Frères made a particular run with 17 as an alternative of 15 jewels. This was the primary time an Angelus 240 was utilized in a wristwatch. The first motion batch was marked 12.55 (December 1955) on the principle plate.

On web page 108 of the present Panerai catalogue 2018 – 2019 it’s written that Angelus 240 calibers have been launched in the beginning of the Forties however there’s completely no proof to assist this declare.


The solely identified 3646 that includes an Angelus 240 together with a Radiomir dial is a typical Rinaldi faux which was offered by Antiquorum in May 2004 (Lot 96). All different 3646s with Angelus 240 and Luminor dials are Rinaldi fakes as effectively. In my opinion, G. Panerai e Figlio by no means put in Angelus 240 actions in common 3646 watches with wire lugs. Ref, 3646 was the one reference made within the Forties. The first post-war reference was Ref. 6152 from 1953. Ref. 6154 got here out in 1954 and Ref. 6152/1 in 1955.

The 2018 – 2019 catalogue additionally states Angelus actions have been launched to cut back put on on the threads of screw-down crowns. This rationalization makes not a lot sense contemplating the GPF 2/56 and a lot of the Ref. 6152/1 watches that includes Angelus 240 actions have a crown-protecting gadget together with a springloaded crown.

Fictional narratives like this originate from Francesco Ferretti, a classic Panerai supplier who turned the trendy Panerai’s advisor for historical past issues since 1997. His tales discovered their means unreflected into catalogues and promotional books.

Anyway, impressed by the Swiss watch trade’s swap to innocent luminous compounds, Panerai’s modified 6152/1s have been to incorporate trendy dials with a tritium-based combination to create a up to date timepiece. Replacing radium-226 with tritium was additionally a logical step to guard G. Panerai e Figlio workers from harmful radiation.

An attention-grabbing discovery made at Ferretti’s wonderful Panerai Museum in Montecatini Terme is the existence of a self-luminous emergency gentle disc engraved with Trilumen Panerai (far left). Trilumen seems to be a fantasy title composed of Trizio (tritium) and Lumen (unit for seen gentle emitted by a given supply). Trilumen and Luminor on the picture beneath appear to be precisely the identical whereas Radiomir (proper) is significantly completely different in color.


Was Trilumen maybe the title initially chosen for Panerai’s tritium-based combination however later changed with Luminor for its sexier sound?

A  New Generation Of Panerai Watches

To promote the brand new 8-days actions and Luminor, Mr. Panerai got here up with an excellent concept of modifying round thirty Ref. 3646 leftovers from WW2 and awarding them to excessive rating officers of the Marina Militare. These watches can be a hyperlink to the fantastic previous of the unique Decima MAS pre September 1943 and on the identical time an indication of Panerai’s functionality to supply up to date instruments.

The watch pictured beneath is such a timepiece. Based on the slimmest model of Ref. 3646 made by Rolex in 1944, Panerai eliminated the wire lugs and welded trendy hornlugs onto the prevailing cushion circumstances.


The low energy reserve Cortebert 618 (36 hours) have been changed with Angelus 240 8-days motion leftovers that had been ordered for the GPF 2/56. All actions present in watches which can be undisputed are marked 12.55 (December 1955).

These have been the primary watches ever to hold the Luminor title. To sugar-coat the entire thing, these dials additionally bore for the primary time within the historical past of Panerai the Marina Militare title. Another novelty was the small seconds hand at 9 o’clock to right away see if the motion was working.

The watch pictured above is a part of the Archivio Storico Panerai, the classic Panerai assortment of the trendy Panerai firm. It comes with an undisputable provenance because it was a part of a classic Panerai lot consisting of six watches handed over to Richemont by the unique Panerai firm after the sale of the Officine Panerai title in March/April 1997.


1 – Orologio Luminor MM storico – Anni 50

Translation: 1 – Luminor watch MM historic – Nineteen Fifties

In the above talked about stock record, the Pre Vendôme folks described the watch as from the Nineteen Fifties, which is wrong. This misguided evaluation occured as a result of easy indisputable fact that the Pre Vendôme guys had very restricted data in regards to the time earlier than Giuseppe Panerai’s loss of life in 1972.

Similar mistaken statements could be present in Pre Vendôme watch adverts the place it was said Luigi Durand de la Penne wore a Luminor when he attacked the HMS Valiant in December 1941 or that the Luminor was designed in 1938.


Luminor, l’orologio degli incursori della Marina Militare, è tornato per farvi rivivere la sua leggenda. Progettato nel 1938 per i reparti d’assalto della Regia Marina, viene proposto dalla Panerai riprodotto sui disegni construtivi dell’epoca.

Translation: Luminor, the watch of the Navy raiders of the Marina Militare, is again to revive its legend. Designed in 1938 for the assault models of the Regia Marina, it’s supplied by Panerai, reproduced based mostly on technical drawings of the period. 

The Mare Nostrum prototype – which undoubtly is a Nineteen Fifties design based mostly on devices from 1954 – was described as a prototype from 1943.

Giuseppe Panerai was born in 1903. With thirtyone, he needed to take over the reins of G. Panerai e Figlio (Guido Panerai and Son) after the loss of life of his father Guido. Giuseppe Panerai was a enterprise proprietor of the old-fashioned who managed all the things himself. With his loss of life on February 7, 1972, all data in regards to the watches died with him.


Modified 3646s with welded hornlugs are generally known as Transitional 3646. This is a deceptive title since they don’t symbolize a transition from wire lugs to lugs carved out of the identical block of metal because the case. As a matter of reality, there was no transition. The manufacturing of Ref. 3646 resulted in 1944 and in 1952/53, Rolex made Ref. 6152, the primary mannequin with conventional hornlugs. Rolex had used tradional hornlugs in watches made for the civilian market since 1931.

Welded hornlugs 3646s have been geared up with show casebacks to exhibit the brand new 8-days actions. All awarded watches have been numbered (Matr. No 1 – 30).


Apart from the matriculation quantity, these casebacks function one other essential element which holds the reply as to what these watches have been all about. See the big I within the middle of the plexi?


To perceive the that means of the I it’s needed to take a look at the broader context during which these watches have been made. These have been the primary watches to ever function tritium-based Luminor dials and curiously, some Luminor vials discovered on the Villino Panerai in Florence have labels that includes the exact same I. Tipo I is Italian for Type I.


This isn’t any coincidence. The I stands for innocuo, the Italian phrase for innocent, and refers back to the new tritium-based luminous compound.

As talked about earlier, there’s quite a lot of confusion concerning these items. Some Panerai fans nonetheless imagine these watches symbolize a transition between wire lugs and conventional hornlugs however one take a look at the actions is sufficient to perceive they don’t seem to be.

The image beneath reveals the Angelus 240 motion of Matr. No. 2, the bottom identified instance. The motion is clearly marked 12.55 (December 1955).


By December 1955, Rolex had already equipped Ref. 6152, 6154 and 6152/1, all with conventional hornlugs carved from the identical block of metal because the case.

The image beneath was taken in August 2019 on the newly established Panerai museum within the Panerai boutique in Florence and reveals the modified 3646 handed over to Richemont by the unique Panerai firm.

The watch is wrongly described as Radiomir 1940 with conventional horn lugs milled from a single metallic block.


This kind of watches have hornlugs that have been welded onto present Ref. 3646 cushion circumstances from WW2. The lugs are clearly NOT milled from the identical block because the case as described by the trendy Panerai firm.

Some examples which aren’t as completely completed because the piece from the Archivio Storico Panerai present fairly tough welding marks.


Around 30 items of those specifically modified watches have been assembled (Matr. No. 1 – 30) to be awarded to excessive rating officers of the Navy and veterans of the Decima MAS or their households. According to Panerai – Una Storia Italiana, any such watches with show caseback have been by no means utilized in motion (web page 235).

G. Panerai e Figlio quickly launched a second batch that includes the exact same trendy components (Luminor plus Angelus 240 plus show caseback) however this time based mostly on Ref. 6152/1.

The subsequent image reveals Matr. No. 56, a chunk which was given to the household of Alcide Pedretti, a Decima MAS member who was killed – along with Teseo Tesei – throughout a failed Maiale assault on the British Naval Base in Malta in July 1941 and was awarded a Gold Medal of Military Valour autopsy.

Ref. 6152/1 – Matr. No. 56 (Photo: Luciano Cipullo)


The second batch featured the exact same 4-liner dial with Marina Militare Luminor Panerai engravings as the primary batch based mostly on Ref. 3646.

This kind of watches have been geared up with Angelus 240 calibers marked MAI.61 (May 1961). The date stamp on the motion most important plate doesn’t essentially confer with the manufacturing date of the motion. It is merely the manufacturing date of the principle plate.

These watches have virtually equivalent show casebacks as the primary batch and the I for innocuo (harmnless) is ever current.

Ref. 6152/1 – Matr. No. 56 show case again (Photo: Luciano Cipullo)


The second batch consisted once more of round 30 items (Matr. No. 31 – 60). The lowest identified  matriculation quantity is 35, the best 57.

Giuseppe Panerai’s plan labored out. Thanks to this little bribe, the curiosity in Panerai watches was revived and new orders have been quickly positioned. In addition, all Ref. 6152/1 watches that have been already in service for the reason that mid Nineteen Fifties have been up to date with Luminor/Marina Militare dials as soon as the Radiomir dials had deteriorated. This explains why some 6152/1 watches with out the Panerai crown-protecting gadget function Luminor/Marina Militare dials.

One massive drawback of Ref. 6152/1 was the entire lack of a time-recording rotating bezel that had turn out to be a typical function for diving watches. To overcome this problem, Panerai experimented with a rotating bezel manufactured from plexi which was held in place by three tiny spring-loaded pins on small grooves utilized to the plexy crystal.


The means the bezel was mounted was not a viable resolution because it got here off simply. Only a handful watches have been geared up with any such bezel.

According to Panerai – Una Storia Italiana, the final order of Panerai watches made by the Marina Militare was positioned on July 12, 1968. 21 items of Ref. 6152/1 with Angelus 240 actions and SMZ (Sommozzatore = diver) engravings have been ordered (web page 248).

There is one 6152/1 with case quantity 124982 that includes an Angelus 240 motion marked 12.55 (December 1955). Some argued that is the proof Luminor was certainly launched within the Nineteen Fifties and never within the Sixties. Well, it’s not. The watch in query has a caseback with SMZ No. 186 engravings. This is the best identified SMZ quantity which was a part of the final 21 items ordered in July 1968. The motion was both changed or they put in a leftover from the GPF 2/56 order.


The manufacturing of tritium is an advanced course of that requires huge infrastructure like nuclear reactors or particle accelerators. Furthermore, tritium was unobtainable in 1949 which finally led to an enormous delay of the primary American thermonuclear bomb. Unless Giuseppe Panerai had a secret nuclear reactor in his basement, there isn’t a means he may have obtained tritium in 1949.

The information introduced on this article converse for themselves. Panerai’s declare that the unique firm invented a tritium-based compound in 1949 has no foundation in actuality. The referred doc isn’t a patent for a specific invention however merely a trademark registration with none mentioning of tritium.

Giuseppe Panerai got here up with a cool product title and had it registered. Panerai continued to make use of radium-226 all through the Nineteen Fifties and early Sixties because of lack of alternate options, similar to some other dial maker. When the Swiss watch trade switched to tritium-based compounds in 1963/64, Giuseppe Panerai understood the indicators of the time and began growing his personal tritium-based combination utilizing tritium compounds that have been now out there available on the market.

In Italy there was no instant want to exchange radium-226 because it remained authorized so long as the exercise was inside sure limits, even after 1970. Since tritium-based compounds have been a viable alternative for radium and having the protection of his workers in thoughts, Giuseppe Panerai discontinued Radiomir. All new watches delivered to the Marina Militare after 1965 have been geared up with Luminor/Marina Militare dials.

To me, extra attention-grabbing than the entire tritium story, is the existence of Translux, Luminova-style pigments earlier than 1972. If G. Panerai e Figlio developed such pigments so early on, this would actually be groundbreaking and price focussing on.

Thank you on your curiosity.

The Panerai Time Machine

Panerai watches have been formed by traditionally essential occasions. The timeline beneath represents the present state of analysis into classic Panerai watches. Please click on the graphic to obtain the highres model.


This timeline is accessible as a top quality print in two sizes:

  • 120 x 68 cm (47 x 26 inch): EUR 85.00 (plus delivery)
  • 150 x 85 cm (59 x 33 inch): EUR 120.00 (plus delivery)

Printed with HD Inkjet on heavy artificial paper and laminated.

Limited version: 50 items, numbered and signed by Maria Teresa Panerai in Giuseppe Panerai’s very personal laboratory on the historic web site of the Villino Panerai (Panerai Villa) in Florence: Sold out

More info: The historical past of Panerai watches at a look


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