Hi,
I have forged some kitchen knives out of coil spring. I think they were made of 1090 or 5160.
I have polished my blades up to 2000 grit. But the problem is that when I use them for cutting food, some stain (blackish stain) appear on the blade and can only be removed by sanding it with the 2000 grit. Washin do not remove those stain. The worst seems to be when I cut some onion. It make an effect similar to etching the blade.
So, I would like to know if there is a way to protect the blade from this.
tkx a lot