I had some free time this afternoon. I had heard of using vinegar for patinas. As anyone who has sliced acidic fruits and vegetables with carbon steel knives knows, acid will etch and stain steel. Gave Mandu a 35 minute bath with distilled white vineagar.

In just that short of a time, the blade turned a mottled gray.




If I wanted it even darker, I could have left it in longer. This is a very nice light gray patina.