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