I have been searching and searching, but I cant find the English word that is used to describe this.
In Swedish its “blånering”. Its something you usually do to the barrel of a weapon or to the blade of a knife, so it wont rust.
As far as I understand, you heat up the metal, and apply some sort of oil that leaves this surface. Its dark greyish/black, sometimes kind of blue.
Some pictures so you can see what I mean.
Here a bayonet, the shaft and the sheath is “blånerad”. You can see its worn.

This pistol can be bought in two versions, “blånerad” (like the picture) or stainless steel (I reckon its shiny/silverish then).

Please help a desperate man
