What causes these squiggly lines?

[garandman57]

My Krag bayonet, has some very different squiggly lines in the blood groove mainly, but also on the blade.
It is not rust, ive scrubbed & scrubbed with 0000 steel wool.
Does not come off.
Anyone see this on other bayonets?
Thanks for your input.

[oldfoneguy]

That is referred to as patina. The colorful descriptions given by dealers embellish it. It is a result of rust following the grain of the steel and leaving permanent staining. It is generally removed by wire wheeling which also removes a small amount of steel in the process. I strongly recommend against that. It's something that can be lived with as long as the rust is deactivated. Nothing more sinister than that, no secret engraving that had been obliterated years ago.

[capt14k]

It's pitting from rust or black gunk that was removed. Best to leave it because to remove it you need to grind it some and it is always noticeable. Even if you spend the time and put in the effort going at it with 0000 Steel Wool it will be noticeable.

[garandman57]

Thanks for the comments!
I was trying the 0000 to figure out if it was rust.
But want to leave it alone!
I think its really COOL looking!
Never seen it before.
Thanks again!

[Peter Laidler]

I would say that it is part of the inherent metallurgy of the not-so-pure quality of the steel. We call it 'crazing'. But I could be wrong.....