Is it a safe to force patina a blade that might have some rust on it?

[JulianHayes]

As the title implies, I have an old case pen knife that was neglected. There was some rust on the blades and the back spring, so I took some 1500 grit paper and cleaned up the blades and the spring, there is some deeper rust that I am nervous to repair without going too deep into the blade. But I would lie to force patina the blade again, as I do with all of my case CV knives. SO my question is, is that a bad idea? is it dangerous to the blade to force a patina over rust that may be lurking underneath? Will the evil rust fester and grow more quickly under a force patina? what do I do? any help appreciated, thanks, Julian

 

[OHALLUM]

I have an old Barlow that has just what you have described on it's blades. I did the same as you and sanded most of the old rust off, leaving some deep pitted areas of rust I assume. It now has a natural patina, and has had for over a year, and the pitted areas are visible, but they are no different than when I finished "cleaning up" the blades when I got the knife.

Blessings,

Omar

 

[Obsessed with Edges]

Just clean the blade thoroughly of whatever acid you use to force the patina (vinegar, etc.). The existing red rust on the blade isn't very strongly bonded to the steel anyway, and the acid will soften it further. Follow that by scrubbing the blade thoroughly with baking soda (with a little water), which will rub off any of the weakly bonded oxide (both old and new, red and black) and it'll also neutralize the acidic reaction with the steel. Rinse thoroughly with lots of water after the baking soda scrub, and then dry everything off and oil/lube as needed. The forced patina, after the scrubbing, will leave some light grey patina behind. The patina that's still there is the strongly-bonded oxide that will help protect the steel down the road.


David