Quote Originally Posted by Neil Miller View Post
Both are types of metal corrosion. However, steel that has accumulated a thin coating of corrosion, ie a 'patina', over many years is not the same as metal that has corrosive pits in it. In fact the thin patina acts like a protective layer - it is stable, and with moderate care the blade will last for many, many years to come. With pitting we have corrosive elements or particles that attach at random intervals to the steel blade, forming small differences in potential between themselves and the underlying layer (blade) that spreads both outwards and downwards, as Bruno said it oftern travels just under the surface and when the surface is abraded pits are revealed that are more extensive than first thought.

You could call the bad stuff an 'unstable patina' that gives rise to pitting. The following gives an idea of the electro-chemical processes involved:


Regards,
Neil
I like how the video shows how quickly a razor can begin to rust if exposed to water. I'm don't know much about knives, but I vaguely know some people do a forced patina to bring in the protective concept you mentioned.

It's fun looking around the workshop forum. There is so much new info there for someone like myself and even if I don't get into restoration much of it seems like stuff any vintage razor buyer would want to know. Depending on the cost of tools/materials I think this might be something I'd want to tinker with though. I'd love to be able to better select a great Tennis restore from auction pictures one day. Thanks for the response. I know all the info is out there, but for someone brand new the back and forth can help with the learning curve.

Between shaving with a straight for the first time and looking through the workshop forum I've got plenty to keep me busy.