Effects of Rust Bluing on Damascus and Twist Barrels

[J. A. EARLY]

With the number of Damascus and Twist guns that have barrels that have been completely rust blued, is there an effect upon the metal that damages/weakens the barrels or is that an old wives tale? Can they be brought back by removing the blue and then finished correctly? I would think the finish is just on the surface as it can be removed or wear off but others say the rust-bluing penetrates and weakens the metal.

I'm looking for opinions and/or research.

Thanks.