Stainless steel is an alloy which is a metal that is made by combining two or more metallic elements. There are about 150 different grades of stainless steel, but they are not all considered safe for food contact. For stainless steel to be approved as a food contact substance (FCS) by the US Food and Drug Administration (FDA), it has to have a chromium content of at least 16%. The chromium prevents surface corrosion by creating an inert film of chromium oxide. The chromium oxide blocks oxygen diffusion. In other words, it prevents corrosion. While not required by the FDA, nickel makes stainless steel resistant to acidic food. The safest stainless steel for flatware is a stainless steel grade that has both a high percentage of chromium and nickel.
Safest stainless steel for flatware
The most common food safe grade of stainless steel is grade 304 stainless steel, also known as 18/10 stainless steel. For most every day applications, grade 304 stainless steel will more than suffice. The only time you would need a more corrosive resistant grade, such as grade 316 stainless steel, is if you lived in a high salt environment such as a beach house or boat.
If price is not an issue, the absolute best grade of stainless steel for food contact is grade 316. The higher content of nickel and the addition of molybdenum increases its corrosion resistance.
Lower quality stainless steel for flatware
While both grade 430, also known as 18/0 stainless steel, and series 200 stainless steel are considered safe for food contact based off of the FDA’s guidelines, it is recommended that they both be avoided. These grades of stainless steel save on costs by omitting nickel. As a result, the lack of nickel increases their chances of corrosion and reaction to food. These types of flatware are more often found at restaurants on a budget.
Knives
Knives follow a different rule. If they were to be made with grade 304 or grade 316 stainless steel, they would not keep a sharp edge for long. They need a higher percentage of carbon and a lower percentage of chromium and nickel for a higher hardness. Therefore, kitchen knives are usually made with grade 410 or 420 stainless steel. Hunting knives are a whole other beast. The best material for hunting knives is up for debate, but they can be made with grade 440 stainless steel.
Compositions
| Grade | Iron | Chromium | Nickel | Molybdenum | Manganese | Silicon | Carbon | Phosphorus | Sulfur | |
| 304 | 18/10 | 68.595% | 19% | 9.25% | 2% | 1% | 0.08% | 0.045% | 0.03% | |
| 316 | 65.345% | 17% | 12% | 2.5% | 2% | 1% | 0.08% | 0.045% | 0.03% | |
| 410 | 13/0 | 84.03% | 13% | 0.75% | 1% | 1% | 0.14% | 0.04% | 0.03% | |
| 420 | 83.78% | 14% | 1% | 1% | 0.15% | 0.04% | 0.03% | |||
| 430 | 18/0 | 79.06% | 18% | 0.75% | 1% | 1% | 0.12% | 0.04% | 0.03% | |
| 440A | 78.43% | 18% | 0.75% | 1% | 1% | 0.75% | 0.04% | 0.03% | ||
| 440B | 78.23% | 18% | 0.75% | 1% | 1% | 0.95% | 0.04% | 0.03% | ||
| 440C | 77.98% | 18% | 0.75% | 1% | 1% | 1.2% | 0.04% | 0.03% |
Conclusion
- Safest stainless steel for flatware is grade 316.
- Second safest stainless steel for flatware is grade 304.
- Lower quality stainless steel for flatware is grade 430.