Rust.
Your steel knife contains iron and when iron is exposed to moisture, even just in the air, it produces iron oxide, or rust. And don't be fooled, stainless steel can rust too. Hence the name stain-LESS not stain-PROOF.
When it comes to rust and stains you want to be careful not to use abrasive removal methods as they can cause damage.
Here's what we recommend:
- soak for 3-5 minutes in white vinegar (be sure to avoid white wine, apple cider, balsamic, etc.)
- remove from vinegar, run under water and rub a small amount of Bar Keepers Friend on with a cloth
- rinse and dry immediately
What we love about Bar Keepers Friend is it contains oxalic acid, which breaks down deposits but is non-abrasive.
Until next time,
Knifey Wifey