The term “mirror stainless steel plate” refers to the surface finish of the steel, but it also has different grades. This grade refers to the roughness of the stainless steel surface, and different grades correspond to different surface finishes. For example, 8k and 12k mirror stainless steel have different surface effects, but this differentiation is not precise enough.
The use of a “K number” to distinguish the surface effect of stainless steel is a general concept and can be difficult to differentiate without a comparison.
We have created a list to help identify different grades of stainless steel.
| Surface grade | Surface roughness | Surface effect |
| Stainless steel surface finish Grade 14 | Ra 0.012~0.03μm | 14k mirror stainless steel with excellent surface effect (ultra-fine polished stainless steel) |
| Stainless steel surface finish Grade 13 | Ra 0.015~0.02μm | 12k mirror stainless steel with excellent surface effect (ultra-precision polished stainless steel) |
| Stainless steel surface finish Grade 12 | Ra 0.02~0.16μm | 10k mirror stainless steel with excellent surface effect (fine polished stainless steel) |
| Stainless steel surface finish Grade 11 | Ra 0.1 ~0.2μm | 8k mirror stainless steel with good surface effect (fine polished stainless steel) |
| Stainless steel surface finish Grade 10 | Ra 0.2 ~0.3μm | 6k mirror stainless steel, BA stainless steel, original state of steel factory shipment |
| Stainless steel surface finish Grade 9 | Ra 0.4 μm | There is almost no brightness at 4k, also known as no brightness at 2B (fog) |
| Stainless steel surface finish Grade 8 | Ra 0.8 μm | No mirror effect, can slightly identify the processing trace, and the unpolished surface |
| Stainless steel surface finish Grade 7 | Ra 1.6 μm | No mirror effect, able to identify the direction of processing traces, unpolished surface |
| Stainless steel surface finish Grade 6 | Ra 3.2 μm | No mirror effect, no visible processing trace, unpolished surface |
| Stainless steel surface finish Grade 5 | Ra 6.3 μm | No mirror effect, slight machining trace, unpolished surface |
| Stainless steel surface finish Grade 4 | Ra 12.5 μm | No mirror effect, visible processing trace, unpolished surface |
| Stainless steel surface finish Grade 3 | Ra 25 μm | There is no mirror effect, the surface is very rough, there are very obvious machining marks, and the surface is unpolished |
