dark spots on blade

[winst]

Can anyone tell me how to remove these deep dark stains from an old knife blade--it doesn't appear to be rust but maybe deep lube stains???

[just bob]

Kind of like cleaning carpet, isn’t it? You don’t want to do further damage and should test first in an inconspicuous area. So maybe first test on a China or low value knife. Paint thinner may work? Goof Off is a good product. 0000 steel wool only leaves very fine scratches. When you’re done wash the blade with dish soap and rinse. Use a good quality metal polish when the blade is dry.

[cudgee]

Some photos would be handy.