One word in an earlier post tells all that needs to be told .... onion .
Cutting onions will instantly put a patina on any carbon steel blade. It is actually similar to gun blue in as much as it is a type of corrosion. Usefully, it's a corrosion that can actually help prevent further corrosion as it effectively seals the surface of the steel from the atmosphere etc.
Cut living beech or oak with a highly polished carbon steel blade if you want to see what wood acids will do
Cutting onions will instantly put a patina on any carbon steel blade. It is actually similar to gun blue in as much as it is a type of corrosion. Usefully, it's a corrosion that can actually help prevent further corrosion as it effectively seals the surface of the steel from the atmosphere etc.
Cut living beech or oak with a highly polished carbon steel blade if you want to see what wood acids will do
