Hi Everyone,
I'm starting this thread expressly to document and discuss information related to materials used in the construction of G-Shock (and other Casio sub-brand) watches. The focus will be on the polymeric parts which are sometimes referred to as "resin."
Resin is a generic term in polymer science and manufacturing and is equivalent to saying that a shiny, silvery, hard part is made of "metal." In other words, it represents the broadest possible classification of a category of materials meaning, generally, "synthetic polymer" or more colloquially, "plastic."
In this thread, I recommend the following relevant (sub)classifications:
The hard but non-glassy feeling case resin seems to be the exclusive material of construction of all non-metal, non-composite cases. It feels dense and hard, but not like glass. It has a surface softness such that if you drag your fingernail (or a springbar tip) across it, it will leave a mark. Its surface is also slightly lubricious, meaning slippery feeling.
I've guessed that two likely candidate materials could be acetal or a mineral/glass-filled polymer composite like polypropylene or nylon. The main reason is that both of these are reasonably priced materials with good temperature and environmental resistance, and can take semi-precision machining including drilling and tapping for screws and bolts.
Well, today I received an answer to my wonderings. I asked Casio America tech support for the polymer class of the GW-9400 and the GW-6900, as broadly representative of the major lines (including the 5xxx and others). They had to escalate the query to Japan but the response that came back is as follows:
Now, it is unclear that carbon composite cases (e.g., GG-B100 Carbon Core Guard) use the same polymer matrix (nylon) as the glass fiber reinforced cases but I think it's very likely. The reason why is that the only difference need be the replacement of the chopped glass fiber with chopped graphite fiber. With the right fiber treatment and matrix resin formulation, it's essentially a drop-in change during manufacturing. In fact, many composite parts that can be made with glass fiber can also be made with carbon fiber. This holds true for the chopped, long strand, thread, yarn, or woven mat forms of the fibers.
What about the strap then? Let's start with the flexible buckle-type two-piece straps that are so common. throughout the catalog.
This is also, a surprisingly easy question to answer for the vast majority because the identity of the materials embossed right on the injection molded strap parts. It's polyurethane elastomer.
Here are just a few examples from my collection. Note the ">PUR<" code. Casio have settled on this material for its great balance of properties. That it's found in the most expensive to the cheapest (F-91W) watch suggests two things:
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Another class of strap materials would be the composites. By this, we mean carbon fiber composite although other fiber substrates and constructions have been used in the past.
Again, we're helped by parts labeling. And guess what, the matrix resin is also polyurethane as evidenced by the ">PUR-CF20<" designation. I do not know for sure what the "20" after "CF" means. It could designate the percentage loading by mass or volume or perhaps it references a grade. Whatever it means, for the GW-9400 Rangeman and the GW-9300 Mudman, the carbon fiber is most likely there for cosmetic/novelty reasons instead of true, critical functionality. I suggest this on the following basis:
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Finally, the last category of flexible resin straps is "unknown" because they are not labeled with any discernible polymer type designation. They are most often found on older, vintage models and sometimes the straps are more plasticky/hard feeling. I think there's a reasonable likelihood that some of these straps that feel like modern straps are probably made of polyurethane but just not labeled as such. To be certain, we'd have to test the material or identify a period in time when plastic parts labeling requirements or legislation came into force.
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I'd like to know about the Combi bracelets next. But as far as I can tell, there are no identity markings on any of the ones I own. This includes the Combi V2 for squares and the Combi for the Gulfmaster.
Perhaps one of you might want to pose the question to your local Support office?
Let's take a closer look at the bezels next time. It's possible that they are polyurethane as well but we'd need to see markings or hear from Support to be sure.
What I can say is that polyurethanes are a very versatile class of polymer and Casio has likely gotten very expert in their use over decades.
I'm starting this thread expressly to document and discuss information related to materials used in the construction of G-Shock (and other Casio sub-brand) watches. The focus will be on the polymeric parts which are sometimes referred to as "resin."
Resin is a generic term in polymer science and manufacturing and is equivalent to saying that a shiny, silvery, hard part is made of "metal." In other words, it represents the broadest possible classification of a category of materials meaning, generally, "synthetic polymer" or more colloquially, "plastic."
In this thread, I recommend the following relevant (sub)classifications:
- resin - any plastic part that ranges from firm but flexible to hard
- elastomer - any plastic part that is stretchy or easily bent of flexed up to 180 degrees without damage
- composite - a part consisting of two or more distinct materials intimately commingled
- bezel - the part that substantially overlays the main case of the watch and that may be fastened to the case using clips or bolts
- case - the main, central housing for the module/movement of the watch
- strap - the lengths of material that fasten the watch to the wrist of the wearer
The hard but non-glassy feeling case resin seems to be the exclusive material of construction of all non-metal, non-composite cases. It feels dense and hard, but not like glass. It has a surface softness such that if you drag your fingernail (or a springbar tip) across it, it will leave a mark. Its surface is also slightly lubricious, meaning slippery feeling.
I've guessed that two likely candidate materials could be acetal or a mineral/glass-filled polymer composite like polypropylene or nylon. The main reason is that both of these are reasonably priced materials with good temperature and environmental resistance, and can take semi-precision machining including drilling and tapping for screws and bolts.
Well, today I received an answer to my wonderings. I asked Casio America tech support for the polymer class of the GW-9400 and the GW-6900, as broadly representative of the major lines (including the 5xxx and others). They had to escalate the query to Japan but the response that came back is as follows:
So consider the mystery solved.
Now, it is unclear that carbon composite cases (e.g., GG-B100 Carbon Core Guard) use the same polymer matrix (nylon) as the glass fiber reinforced cases but I think it's very likely. The reason why is that the only difference need be the replacement of the chopped glass fiber with chopped graphite fiber. With the right fiber treatment and matrix resin formulation, it's essentially a drop-in change during manufacturing. In fact, many composite parts that can be made with glass fiber can also be made with carbon fiber. This holds true for the chopped, long strand, thread, yarn, or woven mat forms of the fibers.
What about the strap then? Let's start with the flexible buckle-type two-piece straps that are so common. throughout the catalog.
This is also, a surprisingly easy question to answer for the vast majority because the identity of the materials embossed right on the injection molded strap parts. It's polyurethane elastomer.
Here are just a few examples from my collection. Note the ">PUR<" code. Casio have settled on this material for its great balance of properties. That it's found in the most expensive to the cheapest (F-91W) watch suggests two things:
- They use it in substantial volumes such that they get a good price on the resin
- They have optimized their production process to be highly efficient and cost effective over the years
Another class of strap materials would be the composites. By this, we mean carbon fiber composite although other fiber substrates and constructions have been used in the past.
Again, we're helped by parts labeling. And guess what, the matrix resin is also polyurethane as evidenced by the ">PUR-CF20<" designation. I do not know for sure what the "20" after "CF" means. It could designate the percentage loading by mass or volume or perhaps it references a grade. Whatever it means, for the GW-9400 Rangeman and the GW-9300 Mudman, the carbon fiber is most likely there for cosmetic/novelty reasons instead of true, critical functionality. I suggest this on the following basis:
- this kind of simple weave fabric in a flexible matrix adds very little stiffness if any at all
- the fabric is laid on the bias, with a 45-degree angle between the warp and the long direction, meaning that it will contribute little additional tensile strength when you pull on the ends of the strap
- the matrix resin is clear to provide a view of the fiber
Finally, the last category of flexible resin straps is "unknown" because they are not labeled with any discernible polymer type designation. They are most often found on older, vintage models and sometimes the straps are more plasticky/hard feeling. I think there's a reasonable likelihood that some of these straps that feel like modern straps are probably made of polyurethane but just not labeled as such. To be certain, we'd have to test the material or identify a period in time when plastic parts labeling requirements or legislation came into force.
I'd like to know about the Combi bracelets next. But as far as I can tell, there are no identity markings on any of the ones I own. This includes the Combi V2 for squares and the Combi for the Gulfmaster.
Perhaps one of you might want to pose the question to your local Support office?
Let's take a closer look at the bezels next time. It's possible that they are polyurethane as well but we'd need to see markings or hear from Support to be sure.
What I can say is that polyurethanes are a very versatile class of polymer and Casio has likely gotten very expert in their use over decades.
