What 304 and 316L Actually Are
Ask ten hardware suppliers what their parts are made of and most will say "stainless steel" and stop there. That answer is close to meaningless. Stainless is a family of alloys, not a single material, and the gap between the cheapest and the best is wide enough to decide whether your bag looks the same in five years or does not.
Two grades matter for leather goods. 304 is the common one — roughly 18% chromium and 8% nickel. It is what most kitchen sinks, cutlery and food equipment are made from. It does not rust in normal use, it polishes beautifully, and it costs less. For a bag that lives indoors and in cities, 304 is entirely adequate.
316L adds two to three percent molybdenum. That single addition changes how the alloy behaves around chlorides — salt air, sweat, seawater, de-icing salt on winter streets. Where 304 can eventually develop small pits in those conditions, 316L holds. It is why the grade is standard for marine fittings and coastal architecture, and it is what every piece of Hility hardware is machined from.
Why the "L" Matters
The L stands for low carbon — under 0.03%, against 0.08% for standard 316. It sounds like a rounding error. It is not.
When stainless is heated, carbon wants to bond with chromium and settle along the grain boundaries. Every atom of chromium that does this is an atom no longer protecting the surface, and the metal becomes vulnerable exactly along those lines. This is why some welded stainless parts corrode at the weld and nowhere else. Keeping carbon low largely prevents it. On a D-ring or an O-ring, which is welded closed by definition, the difference between 316 and 316L is the difference between a joint that lasts and a joint that becomes the weak point.
The Same Alloy Used in Surgery and Food Production
304 is the standard food-contact grade worldwide. 316L is what you find in pharmaceutical piping, brewing tanks, surgical instruments and body jewellery — anywhere metal touches something that cannot tolerate contamination. Implant manufacturers use a vacuum-remelted version of the same alloy for exactly this reason.
That matters for a bag because hardware touches skin all day. A shoulder strap sits against a neck. A hook rides against a wrist. Both are in contact with sweat for hours. The alloys that are trusted inside the human body are the ones least likely to react on the outside of it.
How Zinc Alloy Hardware Is Made
Almost all inexpensive bag hardware is zinc alloy — zamak — pressure die-cast in a mould. The process is fast and cheap and reproduces complex shapes beautifully, which is why it dominates the market. There is nothing dishonest about it and it has real advantages.
But zinc on its own is dull grey and corrodes readily. So every zinc casting has to be electroplated: layers of copper, then nickel, then chrome or gold, built up in chemical baths. What you are holding is not a metal part with a finish. It is a soft, reactive core wearing a coat a few microns thick.
Plating Versus Solid Metal
A few microns is not much. It is roughly the thickness of a soap bubble's wall. It survives the showroom easily, and it survives a year of light use. What it does not survive is a thumb pressing the same spot on a swivel hook several times a day for a decade.
When the coat wears through, the zinc underneath is exposed and begins to corrode. You get a dull patch, then white powder, then pitting. The part is not repairable, because there is no good metal underneath to re-polish back to. A solid stainless part has no such layer. Machine off the top of it and you find the same alloy you started with, which is why a scratched stainless hook can be polished back to new and a plated one cannot.
Where Our Gold Finish Fits In
Being straight about this: our silver pieces are bare 316L, polished and nothing else. Our gold pieces carry a 24K PVD coating, so they do have a surface layer.
The difference is what sits underneath and how the layer is applied. PVD is deposited in a vacuum chamber and bonds far harder than an electroplated film — it is the same process used on high-end watch cases. And in the worst case, if a gold PVD piece is worn hard for years and the colour thins at a contact point, what shows through is polished stainless steel, not corroding zinc. The part keeps working and keeps looking like metal. On plated zinc, wear-through is the beginning of the end.
The Environmental Difference Nobody Advertises
Electroplating is chemically demanding work. The baths involve heavy metal salts, and traditional processes have used cyanide and hexavalent chromium — both now heavily restricted in the EU, and both requiring serious wastewater treatment that not every workshop actually performs. The plating on cheap hardware is cheap partly because that treatment was skipped somewhere upstream.
Solid stainless skips the entire step. There is no bath, no rinse water, no sludge. Stainless is also among the most recycled materials in industry — it can be melted and re-alloyed indefinitely without losing its properties, and most new stainless already contains a substantial share of scrap. A plated zinc casting is far harder to recycle cleanly, because the coating layers contaminate the melt. If you are building a brand around leather that is meant to last decades, it is worth knowing which of the two metals is designed to last with it.
When Zinc Alloy Still Makes Sense
It would be dishonest to say stainless wins every time. Zinc die-casting handles ornate, sculptural shapes that are difficult or expensive to machine in stainless. It is much cheaper per piece, which matters at volume. And for a seasonal product, a promotional item, or a bag priced to sell fast, paying four times more for hardware that outlives the leather is simply bad engineering.
The question is what you are making. If the bag is meant to be repaired, resold and handed on, the hardware should be able to go the distance too. If it is not, use zinc and spend the money elsewhere. What you should never do is pay premium prices for plated zinc sold as though it were something else.
How to Tell Them Apart
Weight is the first clue, but it can mislead — zinc is denser than you expect. A magnet is better: 316L is largely non-magnetic in its annealed state, and a strong magnet will barely grip it, while plated steel will stick hard. Look at the inside of a D-ring or the back of a bag foot, where plating is thinnest and finishing is sloppiest.
The simplest test is time. Leave a sample in a humid room for a month, or carry it in a pocket through a summer. Solid stainless will look the same. Plated zinc will start telling you what it really is.
Conclusion
Hardware is a small share of what a bag costs and a large share of how it is judged. 304 is a sound, honest choice for most work. 316L is what you use when the piece has to survive salt, sweat and years. Both are solid metal all the way through, and that is the part no coating can imitate.
Every piece we make is machined from 316L. Browse the best sellers, or send us a sketch and we will tell you what we would use.