I’ve had a set of LN chisels housed in their leather tool roll for at least 25
years. They are not my everyday chisels. Not a speck of rust. Even more
remarkable (if leather is going to be accused of contributing to rust) is my
dad’s WW II military issued knife, complete with belt-looped leather sheath.
This 80+ year old treasure has been removed from its sheath no more than 10
times in the last 60 years. Again, not a speck of rust. I assume the LN tool
roll is veggie tanned leather, but I have no idea what type the knife sheath is.
Since we both live in the SF Bay Area with similar climate conditions, I wonder
if something else may have contributed to your rust issues.