One of the things that determines the quality of a watch is its case. No matter how good a watch looks, if the case is poorly made, you will eventually stop using it. So what determines the quality of a case? This time, I would like to talk about the case material. The first thing to look at, before considering luxury, is whether or not it will cause allergies.
Among current wristwatches, the Bulgari Octo Finissimo Automatic is a rare example of a watch that uses pure titanium for its exterior. It's difficult to achieve the so-called high-end finish, but instead, it's sandblasted to create a matte finish. It's a clever use of titanium.
●What materials do not cause allergies?
People often have allergies when using metal products. Materials that are likely to cause allergies include nickel, lead, cobalt, and chromium (hexavalent chromium). These materials (especially nickel) are rarely used in modern watches. However, they may still be found in inexpensive plated cases.
In contrast, gold and silver are less likely to cause allergies, and 100% pure platinum is virtually allergenic. However, the gold, silver, and platinum used in watch cases contain additives to increase hardness or change color, which is why watches with gold, silver, or platinum cases often cause allergies.
Stainless steel, widely used in the watch industry, is also hypoallergenic, but the likelihood of causing allergies varies depending on the type. In terms of likelihood of causing allergies, 904L, used by Rolex and some Girard-Perregaux brands, is the least likely to cause allergies, followed by 316L and 304L. In other words, those who are concerned about allergies should choose a material of 316L or higher, even if it is stainless steel. However, some inexpensive watches have 316L cases but 304L bracelets. People with allergies should be careful.
At present, the only materials that are virtually hypoallergenic are pure titanium and tantalum. However, these two materials are dark in color and difficult to process, making them less likely to give off a luxurious feel. For this reason, most manufacturers use titanium alloys containing additives for watch cases and bracelets. A good example would be the "bright titanium" used by IWC, Panerai, and Grand Seiko. Because it contains additives, it is more likely to cause allergies than pure titanium, but the possibility is much smaller than with other metals.
Naturally, non-metallic materials do not cause metal allergies. Ceramics, artificial sapphire, carbon, and plastic are all safe materials for people prone to allergies.
・Allergy-causing materials
Nickel, lead, cobalt, chromium (hexavalent chromium), etc.
・Hypoallergenic material
Gold, silver, platinum, stainless steel 316L or higher, pure titanium, tantalum, etc.
・Virtually allergy-free material
Ceramics, artificial sapphire, carbon, plastic, etc.
*Note: Be careful! Even leather straps can cause allergies.
Currently, many leather straps are tanned with a chemical called chromium. However, the chromium used today is not hexavalent chromium, which can cause allergies, but trivalent chromium, which does not (only available in Europe and Japan), so modern leather straps are basically allergy-free. It is a mistake to think that chrome-tanned leather causes allergies. However, if you use a leather strap for a long period of time due to the effects of ultraviolet rays and sweat, the trivalent chromium can change to hexavalent chromium, which can cause allergies.
In other words, if you are allergic to watches with leather straps, we recommend replacing the damaged leather strap. This is because there is a high possibility that the chromium content in deteriorated leather straps has changed from trivalent to hexavalent. Incidentally, the leather straps used by Citizen are specially treated to convert hexavalent chromium back to trivalent chromium. Therefore, in theory, they do not cause allergies. If you are allergic but still want to wear a watch with a leather strap, choosing a Citizen watch may be a good choice.
Many watch manufacturers are now focusing on measures to combat allergies. Citizen, a Japanese watch manufacturer, is one of the most advanced in this area. The leather straps used by Citizen are not only not tanned with hexavalent chromium, which can cause allergies, but are also treated to prevent trivalent chromium from becoming hexavalent chromium.
