Orange Patina or Rust?

[DowntonDC]

Quick question for the forum. I was cutting a bunch of tomatoes for pico de gallo this afternoon with my 240mm Toyama dama gyuto and afterwards noticed some areas of orange/red (pics attached). The blade was wiped/dried a few times, but there was a few minute stretch where the tomato juice was on the blade. I did the paper towel test afterwards to see if it wipes off (proving it was rust), but it came out clean. That said, wondering what everyone thinks — patina or rust?

 

[M1k3]

If it doesn't rub off or have texture, it's patina.

 

[miggus]

Hmm my suspicion would be that it is very superficial rust. These iron claddings can react quickly, and it is a bit suspicious that the spots are so concentrated. It will probably stabilize if you keep wiping your blade in a timely manner. I would take some baking powder with a cosmetics pad and a few drops of water and wipe it off though.

 

[superworrier]

IMO ugly patina but "rust or patina" might be a false question. Somewhere in between? I think this sort of rustina doesn't really cause problems afaik

 

[DowntonDC]

Hmm my suspicion would be that it is very superficial rust. These iron claddings can react quickly, and it is a bit suspicious that the spots are so concentrated. It will probably stabilize if you keep wiping your blade in a timely manner. I would take some baking powder with a cosmetics pad and a few drops of water and wipe it off though.

This was super helpful. I ended up taking a baking soda + water + makeup pad to the spots and they came right off. Best of all, that nice gray/blue patina I had around it stayed put. Thanks for the tip!

 

[WildBoar]

I think your knife was pissed that you were working with January tomatoes...