In the world of body piercing, titanium is often regarded as the “gold standard.” However, when you dig into the specifications, you’ll frequently encounter two terms: ASTM F136 and Grade 23 (G23).
While they are often used interchangeably in marketing, they represent different things—one is a strict material standard, while the other is a broad chemical grade. Understanding the nuance is vital for anyone looking for high-quality jewelry.
Let’s break it down.
The Definitions: Standard vs. Grade
To understand the difference, we first have to distinguish between a Grade and a Standard.
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Grade 23 (Ti-6Al-4V ELI): This is a specific alloy of titanium. The "ELI" stands for “Extra Low Interstitials,” meaning it has reduced levels of oxygen, nitrogen, and iron compared to standard Grade 5 titanium. This makes it more ductile and improves its fracture toughness.
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ASTM F136: This is a technical standard set by the American Society for Testing and Materials. It doesn't just specify the chemistry (which happens to be G23); it dictates the entire manufacturing process, finish, and testing requirements necessary for the metal to be used in surgical implants.
Simply put, all ASTM F136 titanium is G23, but not all G23 titanium meets the ASTM F136 standard for medical implantation.
Chemical Composition
Both materials are alpha-beta wrought alloys. Their primary components are Titanium, Aluminum, and Vanadium, as seen in the table below:
By keeping oxygen and iron levels extremely low, the metal becomes less brittle and more resistant to the harsh environment inside the human body.
Why ASTM F136 Matters for Piercings
If you are buying jewelry, "G23" is a common label, but it can be misleading. Because G23 is just a chemical recipe, "industrial" G23 might be processed in a way that leaves surface imperfections or internal structural flaws.
ASTM F136 compliance ensures:
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Biocompatibility: The material is proven to be non-reactive with human tissue.
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Surface Finish: The standard requires a specific quality of finish, reducing the microscopic "nooks and crannies" where bacteria can grow.
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Strict Documentation: Manufacturers must provide "Mill Certificates" to prove the metal was tested and meets every requirement of the F136 standard.
Comparison Summary
Final Verdict
If you are looking for the safest possible material for your piercings, ASTM F136 titanium is the best option for you. Luckily, at Oh Kira!, we only use ASTM F136 titanium so you can be sure that your ears are getting the best possible material and sparkle.