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Discussion Starter · #1 · (Edited)
The big three Japanese watchmakers have been quietly adding scratch-resistant watch cases and bracelets to their lineup since the 90s, especially Citizen.

To date, very few of these watches have been offered to the international market, which explains the dearth of English literature on these technologies.

I'd like to offer a brief walk-through of the various terms one will come across shopping for a high-end JDM quartz.

First, trademarks.

Duratect is a marketing term registered by Citizen. It is Japlish for dura-techko or durable technology. A Duratect marked watch (on the caseback) has been surface treated, but a variety of methods are used on different models to achieve different levels of hardness and finish. In short, it is not descriptive to say Duratect. Rather the type of Duratect, for example, TIN, TIC, PTIC, MRK, DLC, GTIC, IP or combinations thereof must be specified.

[This is analogous to saying "that is a Citizen". No material information is communicated because Citizen has too many model lines to begin with.]

Brightz and Diashield are registered by Seiko. Brightz is a Seiko developed Ti alloy that's 30% harder than steel, and much harder than regular Ti. The main advantage though, is it's virtually indistinguishable from SS. A Brightz watch scratches about as easily as an SS one, but is much lighter.

Diashield is Seiko's version of DLC, and many new JDM models are Diashield treated. These include SS, Ti and Brightz models. Unfortunately, it appears the Diashield quality correlates with price band. The performance and aesthetics of a Diashield Spirit lags behind a Brightz, for example. It's possible the softer Ti on the Spirit is to blame though.

DLC, CVD (TIC/TIN and similar), IP etc refer to the hardening technologies, as they are commonly known. Casio employs all these methods in their Oceanus and MRG lines, which are Ti only. The only difference between Casio and their competitors is the absence of branding such as Duratect (a rather confusing term) and Diashield.

Next time the question "Which is better, Duratec or bright?" comes up, just note that 1) the spelling is way off and 2) the answer is way more involved than a yes-no.

I hope this short vocab guide makes it easier for the confused.

I'll take a stab at the how-to in metals hardening if there is interest.
 

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Great post, RPF! I've often wondered about the whole process of surface-hardening/coating and have been confused by the trademarked names of the various processes. This helps a lot.

Do you have some insights into ease of repair or scratch removal with these finishes? For example, I've read that the Seiko Brightz titanium alloy is very hard to refinish or polish and usually needs to be sent back to Seiko when refurbishing of the finish is needed.
 

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Great information RPF. This is long overdue as most don't realize that there are different levels of Duratect and Diashield. To further confuse matters, I've seen instances with Citizen of Duratect branded watches not being all Duratect treated. So you might see that the watch head is Duratect, but the bracelet isn't or I remember one instance years ago where everything but the bezel (non diver) was Duratect treated. It's the kind of stuff that drives collectors nuts!

Thanks for sharing!
 

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Great information RPF. This is long overdue as most don't realize that there are different levels of Duratect and Diashield. To further confuse matters, I've seen instances with Citizen of Duratect branded watches not being all Duratect treated. So you might see that the watch head is Duratect, but the bracelet isn't or I remember one instance years ago where everything but the bezel (non diver) was Duratect treated. It's the kind of stuff that drives collectors nuts!

Thanks for sharing!
Thanks Bill! I'd love to hear about hardening technologies. And the technos who hang here would too, I bet. I've seen a few posts in the dive forum and we have had a few too (yours?).

I think casing technology is one of the real achievements of watch technology. We have tended to focus on movements but I think watch cases often differ as much as movements.

The 70s had some fiberglass cases (I have a Tissot with one) and the 90s brought us ceramics (again a Tissot for me).

Indeed, what I most admire about Rolex are its cases.

So more info on case technology, please!
 

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Thanks Bill! I'd love to hear about hardening technologies.
Second the motion! If posting the details of how is a bit onerous, descriptions of the what would be a great start. For instance, I know that TiN is Titanium Nitride, TiC is Titanium Carbide, PTiC is Platinum Titanium Carbide (the coating on my beloved The Citizen). I don't know them all, however. If you did, that would be a great adder.
 

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Discussion Starter · #6 ·
Alright.

I'll keep it simple and corrections are welcome.

A harder exterior reduces scratches and resists deformation. This preserves the aesthetics of the watch far longer but there are some tradeoffs, depending on the method employed.

There are many technologies available today but they fall into these categories, broadly speaking.

1. Hard raw materials e.g. Ceramic, Tungsten, Brightz
2. Harder coatings e.g. PVD, DLC, TIC, TICN, PTIC
3. Harden matrix e.g. functionally graded materials, kolsterizing, annealing

Oops. Duty calls. I'll elaborate on them when I'm back tonight.
 

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Discussion Starter · #7 · (Edited)
A short discussion on the above, leaving out the specifics.

1. Hard materials: This is the most straightforward solution employed by Rado, predominantly ceramics and hardmetal. Hardmetal offerings from Chinese case suppliers are also on the rise.

Material strength and fracture toughness is in general, inversely proportional to hardness. Harder materials are more difficult to work with, due in part to the brittle nature.

Unlike SS or other metals shaped by CNC out of case blanks, ceramic/hardmetal cass are sintered from powder fed at high pressure into precision moulds. It is difficult to control tolerances due to machining difficulties post-forming. This affects the water resistance and is one reason (I believe) we have not seen a hardmetal dive watch. Screw backs are also troublesome for ceramics due to torque load.

Note: Sintering is just a fancy way of saying baking.

Overall, hardmetal is comparable in hardness to ceramics but has greater mechanical and fracture toughness. However, it is also much heavier, with a density approaching that of gold (SG 14-17, depending on binder used).

The main disadvantages of these materials are cost, brittleness, finishing difficulties and the high-tech, non-metal look on what is essentially, jewelry.

Note: Brightz is mentioned because this alloy retains the weight and strength attributes of Ti while improving aesthetics and hardness.

2. Hard coatings: Most people are familiar with this, associating PVD with black metal watches.

We can add ion plating, ceramic coatings (rare) and DLC to the mix. Performance varies depending on substrate and thickness but the mechanical strength of the base material (SS, Ti etc) is not compromised. Coatings also improve corrosion resistance, although that's almost never a selling point on watches. (That is one reason why I never understood the use of 904 in watches.)

Application is similar to spray painting in a specialized chamber.

The main disadvantages are limited finishing options and poor ding (unless in tandem with other technologies) and scratch (DLC is an exception) resistance. Scratches that expose bare metal ruin the aesthetics more than on a plain metal watch.

3. Hardened matrix: Standard machining workflow can be employed on traditional materials before the metal is hardened via heat or surface treatment. The finished product has the benefit of precise tolerances, superior wear characteristics and similar aesthetics to the original alloy.

Metals can be hardened two ways, throughout the matrix or just the surface, producing a functionally graded material.

Damasko heat treats their ice-hardened steel to a uniform >60 HrV, similar in hardness to other martensitic steels such as S30V used on premium knives. Quite impressive given the complexity of a watch case compared to a blade.

Better scratch resistance can be achieved through surface treatment, usually by diffusing carbon and nitrogen into the matrix. The hardness decreases with the penetration of the atoms, producing a material that's hard on the outside and tough on the inside.

Sinn's Tegiment and various versions of Citizen's Duratect employ this method. I've been told IWC also treats several of their Ti models in similar fashion but I've not explored this further.

One argument against surface treatment is the eggshell effect. The surface may resist scratches, but risks deformation due to the underlying soft metal. This is a valid concern but it should be highlighted an untreated watch will deform to a greater degree.

Surface treated metals usually appear dull and cannot be refinished by hand.

***

Personally, I consider combinations of 2&3 to be the best compromise in terms of machining, scratch and ding resistance. Currently, Casio, Citizen, Seiko and a couple of Swiss brands have introduced models which are surface hardened, IP coated and DLC-ed. These are probably the best cases around, even though the ceramic/lanthanum/diamond cases of Rado are harder. For one, they have better tolerances, are lighter and mechanically stronger.
 

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Discussion Starter · #8 ·
Do you have some insights into ease of repair or scratch removal with these finishes? For example, I've read that the Seiko Brightz titanium alloy is very hard to refinish or polish and usually needs to be sent back to Seiko when refurbishing of the finish is needed.
I was unable to refinish my Brightz watch satisfactorily. But others have been able to refinish their SD MM to a consistent case finish.

I can only say it doesn't behave like regular SS.

But do note there are DLC-ed Brightz today. Those definitely cannot be refinished. You'll ruin the watch.
 

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Great summary! You should think about a Wikipedia article... There is nowhere a separate treatment of the use of these technologies in watch casing. It would be a worthwhile addition to the Wiki.
 

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So much for the Duratech coating on my Chronomaster.>>

This is what it looked like after approximately 2 years of wear. Not very impressive, IMO.



So I sent the watch back to Japan for a make-over and she came back like this. I bet all they did was polish out the scratches and did not re-apply the Duratech coating.
 

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Re: So much for the Duratech coating on my Chronomaster.>>

Rex, are you absolutely sure that the bracelet was Duratect and not just the watch case? Citizen has done this in the past....put a non Duratect bracelet on a Duratect protected watch case.
 

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I don't have a clue Pete, but it sure appears that way!>>

The watch case got pretty scratched up as well went I sent it in for refinishing. However when it came back the watch looked LITERALLY brand new again.
 

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Re: I don't have a clue Pete, but it sure appears that way!>>

I just bought a two year old Aersopace and the head is perfect but bracelet is really beat, a bit like the one above. I was going to say that they don't use Ti hardening like Citizen but I'm not sure now...

By the way termite posted an interesting technique here to restore Ti : https://www.watchuseek.com/showpost.php?p=2256488&postcount=13
 

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Re: I don't have a clue Pete, but it sure appears that way!>>

Here's a google translation of a citizen.jp page describing their different surface hardening technologies. Regarding the coating technologies they use for their titanium watches, note from the pics at the bottom that their TIC coating (used in the titanium chronomasters?) is much less scratch-resistant than their MRK coating:

Google Translate
 

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Re: I don't have a clue Pete, but it sure appears that way!>>

Here's a google translation of a citizen.jp page describing their different surface hardening technologies. Regarding the coating technologies they use for their titanium watches, note from the pics at the bottom that their TIC coating (used in the titanium chronomasters?) is much less scratch-resistant than their MRK coating:

Google Translate
That Citizen display seems a little hard to understand with any real degree of confidence, being too vague, laden with Japlish, and depending on a somewhat mushy diagram. Nonetheless, if we can believe the Vickers values in the diagram, I personally would not see the TIC (or PTIC) as much less scratch-resistant than the MRK coating that would appear to be used on only their Promaster models, since the two are not that far apart in the diagram. In addition, the DLC process, which is generally believed to be very hard, falls very close to the TIC and PTIC levels in the diagram; thus, I would think that TIC and PTIC can be understood to be very hard. Their "gold" coating, which appears abnormally hard for real gold (which is present on the graph as K18) and obviously isn't, may refer to titanium nitride, a very hard surface process that imparts a gold color. All things considered, too vague, in my opinion, to be very convincing.
 

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Re: I don't have a clue Pete, but it sure appears that way!>>

That Citizen display seems a little hard to understand with any real degree of confidence, being too vague, laden with Japlish, and depending on a somewhat mushy diagram. Nonetheless, if we can believe the Vickers values in the diagram, I personally would not see the TIC (or PTIC) as much less scratch-resistant than the MRK coating that would appear to be used on only their Promaster models, since the two are not that far apart in the diagram. In addition, the DLC process, which is generally believed to be very hard, falls very close to the TIC and PTIC levels in the diagram; thus, I would think that TIC and PTIC can be understood to be very hard. Their "gold" coating, which appears abnormally hard for real gold (which is present on the graph as K18) and obviously isn't, may refer to titanium nitride, a very hard surface process that imparts a gold color. All things considered, too vague, in my opinion, to be very convincing.
I'd agree with you (about the info. being too vague to be reliable) if I were trying to use the page to show how good the TIC is on the Chronomaster. But I'm not; indeed, I'm using it to raise suspicions about its performance, following Rex's expression of disappointment in how well it performed on his watch. More specifically, I'm saying that, in spite of TIC's having an impressive Hv on the chart (similar to that of DLC, which is known to be highly scratch-resistant), the performance difference (as shown in the abrasion test pics) between TIC and MRK (which are, as you point out, not that far separated on the chart) calls into question whether those chart values mean much. I.e., I'm suggesting the abrasion results, and Rex's own experience, both point towards the idea that the Chronomaster *does not* offer the scratch-resistance of DLC (and, more broadly, does not offer impressive scratch-resistance, period), irrespective of what Hv values are claimed for it.

[And there are possible explanations for this: for one, the actual scratch resistance is determined by the hardness of the coating, and the hardness of the supporting material below it (which means it's also affected by the thickness of the coating itself, if the underlying material is soft). So their TIC coating may be both thin and on top of a soft Ti (or, in Rex's case, steel) alloy, which would prevent it from living up to its Hv value, depending on how that Hv was determined. I.e., the Vickers hardness test is designed to determine the hardness of thin films, so it uses very small indentations; the smaller the load, the less chance the thickness of the film and the mechanical properties of the supporting material will play a role in the measurement. So a thin film on top of a soft material, if measured with a sufficiently small load, could have a very high Vickers score, yet not be anywhere near as resistant to real-world scratches as a bulk material with the same Vickers value. And as Citizen itself says on that page: "For surface coating hardness, coating hardness is measured only at low load."]
 
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