It is a common misconception that stainless steel means rust proof. Stainless steel will rust just like carbon steel. To get truly rust proof steel, you would have to add so much chromium that you lose all the benefits of steel. For example, very common stainless steels have very little carbon and a lot of chromium and other elements which inhibit rust. However, these steels will not take an edge. We’ve written an article about what makes a razor sharp. We suggest you read it.
Stainless steel simply “stains less.” Meaning it is more resistant to rust, but not rust proof. Steel is simply iron melded with carbon. Razors are made from heat treated steel. Stainless steel is just carbon steel with chromium added. The chromium won’t prevent rust, it just retards the rust. Therefore, you need to take just as much care for your stainless steel razor as you would your carbon steel razor.