The blades being regularly sprayed with seawater.
Not all steel is created equal, and with over 3,000 grades available, each has a unique composition at the molecular level that affects its performance.
This diversity becomes clear when you test how different blades withstand exposure to seawater.
The corrosion resistance of a knife is crucial in tropical climates like Malaysia.
Cutting food items with this blade of D2 steel and then storing it without proper cleaning will lead to streaks of rust forming within a day.
Whether you’re an angler, hiker or outdoor enthusiast, the last thing you want is for your blade to start rusting within an hour of getting wet.
Even the salt from sweat can cause rust spots on some folding knives when kept in your pocket.
In this informal experiment, five blades made from different grades of steel were exposed to seawater.
A high carbon steel machete is strong and stays sharp even after hard use, but when using it in wet conditions, care must be taken, such as oiling the blade and wiping moisture off regularly or it will rust severely after a few hours.
High carbon steel blades were deliberately excluded as they are known to fare poorly in such conditions. These blades, often used in machetes and survival knives, are tough enough to serve as pry bars, but in wet or humid environments, they require significant care.
The five types of steel tested were:• 420HC: A decades-old grade, known for its ease of sharpening, general corrosion resistance and resilience against chipping or cracking.
• S35VN: A martensitic steel prized for its durability, edge retention and corrosion resistance. It’s expensive, with even small knives costing upwards of RM500.
• 8Cr13MoV: A budget-friendly steel found in knives priced under RM200. It contains 0.8% carbon, 13% chromium and traces of vanadium, providing a balance of hardness, ease of sharpening and moderate stainless qualities.
• San Mai Blue Paper Steel: This Japanese steel is layered with a high carbon core sandwiched between low carbon outer layers at the forge, giving it toughness while maintaining sharpness. San Mai translates to “three flat things”.
• H1: A unique steel known to “never rust”, thanks to the inclusion of nitrogen. However, this comes at the cost of hardness and the edge dulls easily after use.
These names are industrial codes and reputable knife makers always specify the steel used in their blades.
In this test, the five blades were exposed to seawater and regularly sprayed to maintain moisture.
The starting point of the seawater trial for (from left) H1, San Mai Blue Paper Steel, 8Cr13MoV, S35VN and 420HC blades.
Within the first hour, rust spots appeared on the 8Cr13MoV blade, with 420HC showing slight signs of corrosion.
After 24 hours, the 8Cr13MoV blade had started to “bleed rust” and 420HC was not far behind. The San Mai Blue Paper Steel also began rusting around its emblem.
An hour later, rust begins forming on the 8Cr13MoV (centre) blade.
Commonly, the engravings on a knife are done with high carbon steel tools, so microscopic bits of the tool steel would have found its way into the spot that was engraved.
By the 40-hour mark, the 8Cr13MoV and 420HC blades were heavily pitted and no longer fit for hard use.
After 24 hours, rust spots riddle the 8Cr13MoV (centre) and 420HC (right) blades.
The S35VN and San Mai Blue Paper Steel fared better, with only minor pitting.
The H1 blade, as expected, showed no signs of rust. However, this blade is not without its drawbacks.
After 40 hours, the 8Cr13MoV (centre) and 420HC (right) blades are deeply pitted with rust and only the H1 (left) remains completely rust-free.
Its softness means the edge dulls quickly – after cutting just a few fish, the blade can start to tear rather than slice. Most H1 users carry a field sharpener to keep the edge honed after frequent use.
In the end, there is no “one knife to rule them all”. Different grades of steel suit different purposes, so pay attention to what steel was used to make your knife.
The mere condensation of sweat on this blade made with 154cm steel is enough to cause rust spots to appear. After cleaning, rust will easily reappear at those spots.
If you are buying a new one, think about the outdoor activity you are getting into before choosing a suitable steel grade.
Always buy from reputable sellers, as knock-offs abound and low-grade steel is often passed off as high-end, sold at a premium.
