Understanding Implant Grade Surgical Steel
For many years I have discussed and debated some of the common misconceptions our industry faces when it comes to the steel used in body jewelry. I hope to help shed some light on this subject, and share some of the research I have done. I am by no means a chemist, but the first time I reviewed a mill certification sheet, I wanted to know more about what was in the jewelry we were putting into our clients. Understanding the materials we use in our shops everyday allows us to better serve both our clients and our industry.
Currently the APP (Association of Professional Piercers) website states the following regarding acceptable steel types:
“Surgical Steel is made of a variety of alloys. Many of them are used for body jewelry, but only a few specific grades are proven biocompatible: steel that is ASTM F-138 compliant or ISO 5832-1 compliant; ISO 10993-(6, 10, or 11) compliant; or (EEC [European] Nickel Directive compliant.”
Taken from http://www.safepiercing.org/piercing/jewelry-for-initial-piercings/ under the Creative Commons Attribution-Noncommercial-No Derivative Works License
While I am not an APP member, the APP is arguably the most accepted voice for the piercing industry. So what exactly does this mean?
The American Society for Testing and Materials Standard (now ASTM International) is a volunteer-based organization with 30,000 members in over 120 countries. The ASTM determines standards for a myriad of industries, and has become the most definitive authority in this field. The standards determined by the ASTM dictate what materials can or cannot be used for any given application. Our industry seems to refer to their standardization more often than any other similar organization (AISI, ISO, et al).
Steel that is ASTM F-138 compliant is steel that has passed the criteria for implantation grade. The criteria for implant grade are based on the presence, or lack of presence of certain elements. The chart below shows the AISI, ASTM, and ISO chemical composition requirements for steel to be considered implant grade:
|AISI max%||ASTM max%||ISO max%|
Now, if you have ever requested a mill certificate from your body jewelry supplier, some of this information may look familiar. It is interesting to note the near identical levels allowed by these three different standardization organizations. But, what exactly is a mill cert and what does it tell you?
For our purposes, a mill cert shows the result of a test that determines the chemical makeup of a batch of steel. If a body jewelry supplier consistently uses steel from the same steel manufacturer, a mill cert test will yield near identical results every time. The tests are done by a third-party lab, and the information is presented in the certification report. If the chemical makeup of the steel exceeds the allowed elemental percentages presented in the chart above, it no longer passes the ASTM F-138 standard, and is not implant grade. Failure to pass the ASTM F-138 indicates that the steel could pose a variety of problems if used for implantation purposes.
Every reputable supplier will be able to produce a mill cert, but the mill cert is only as valid as the supplier’s reputation. It is impossible to test every piece of jewelry a supplier carries. The mill cert is only relevant to the batch that was tested. If the steel manufacturer changes the “recipe,” any of the relevant elements could increase or decrease, causing unforeseen problems in the end result (body piercing). In truth, the best (and only) way to find out if a supplier’s body jewelry is up to par is to try it out. Consistency speaks more volume in our industry than any lab test or mill certification document, so find a supplier you are comfortable with, and stick with them. If you are considering switching suppliers, ask for third-party references, like another studio that buys and uses their jewelry. Our customers have been long-term, repeat buyers. This says an awful lot about our jewelry’s steel composition.
For many years the APP website listed 316LVM ASTM F-138 as the only acceptable type of steel to be used in body piercing. However, this was changed within the past few years and the site now states that F-138 compliant steel is acceptable. There are many types of F-138 compliant steel, but our industry finds 316L and 316LVM to be the best suited for the task. But what does 316L or 316LVM even mean?
The numbers are classification codes; and 316 is a classification code that follows 304. Code 316 steel is softer than 304 steel, which is often used to make pots and pans for use in kitchens. Lower tensile strength allows for increased mutability. This is another reason why 316 is used for body jewelry, as it is easier to shape. The “L” is used to signify “Low” Carbon content. In many instances 304 steel will pass ASTM F-138 tests, but due to the softness of the steel, 316 is preferred.
The “VM” stands for vacuum melted. This is a process that reduces what steel makers refer to as inclusions, tiny impurities that remain in the steel, often at a microscopic level. Vacuum melted also helps to remove the presence of sulfur, phosphorous, and other unwanted gases. There is no lab test that can prove that steel has been vacuum melted. Suppliers who place the VM classification on their steel are doing so by their own merit. Mill certification sheets that list the steel type as 316LVM are somewhat inaccurate. Mill testing should by definition be performed by a third party. If the cert says 316LVM, it has been adjusted by the supplier, or the steel manufacturer is also providing the cert. Either way, I would recommend a second opinion. Vacuum melting does not change the chemical makeup of the steel. It will show the same composition both before and after the vacuum melting process.
Good polishing is necessary for the finished product. Proper polishing of body jewelry minimizes any pitting or scratches, which gives the fresh piercing a higher probability of healing without complication.
I have seen or heard of many piercers and resellers advertising nickel-free steel. There is just no such thing. Steel is an alloy comprised of the elements in the above chart. All steel contains nickel, and as discussed, ASTM F-138 steel has low nickel content. Why is this important? Nickel is a natural allergen. Most people will have some visible skin irritation when exposed to metal with very high nickel content. While 316L and 316LVM have very low nickel contents, there is still a percentage of the population who will have a reaction. We recommend solid medical grade titanium in this case. This is titanium that passes the ASTM F-136 standard. This is the same kind of titanium used in major reconstructive surgery.
While we refer to steel as implant grade, it is important to address the reality that basic body piercings are not implants. Implants are completely contained in the skin. If steel that passes the ASTM F-138 standard is considered implant-safe steel, then 316L and 316LVM steel should be considered more than adequate for body piercing.
In my opinion, the steel is as good as the word of the supplier. Consistency is the key. Our piercers have been using the same steel from the same supplier for over five years. We have seen very few nickel allergies or rejections, and no discoloration. This hard data speaks louder than any mill cert.