Support BladeForums! Paid memberships don't see ads! This is an old blade from a zero tolerance 0620cf that I carried and used for more than a year starting back in 2015 I think. I used this blade for everything from food prep to swimming in the ocean, rivers, lakes many times not being maintained until I got home several days later in some instances. I have never seen this hunk of m390 stain or rust in anyway. I ended up selling the 0620cf but kept this blade, it was sold with a new blade out of 204p. I know this steel WILL rust, I just have never seen it rust in real world use in the time I owned and used it. So we will see what it takes to force some corrosion on m390. The blade was washed with dawn dish soap and scrubbed with alcohol and dried to remove all oils I labeled the areas with what we will be testing it with today : Sea salt Horseradish mustard apple cider vinegar Here is the sea salt: Here is the mustard: Here is the vinegar: Here is the blade with the sea salt, mustard, vinegar: I tried to get the sea salt, mustard and vinegar on both the stonewashed and satin surfaces. Here is the time everything went on: I won't stop until I see some serious freaking rust. I will up the ante if I don't get the corrosion levels that I know can be forced!