cover my knife with this "thing"

[thejazz]

Hi guys, maybe there is an old topic for these things, but I don't know how the process is called, so my search was in vain. Please give advice for covering my black steel knife with something close to this.

Thanks.

Best regards!

 

[thejazz]

Found it! Black oxide.. saw it in another post 5 mins after posting this one.. sorry guys!