Durability of Carbonia Blue vs. Hot (salt) Blue.

[Virginia Gentleman]

Carbonia blue looks more translucent that hot blue and I am curious of anyone knows if it is done properly how well it holds up over the long haul to today's hot blue?  Some good hot blue jobs can look very close to a carbonia blue if prepped and kept in the correct temperature range and if the bluing salts are in the correct ratio.  USFA offers both one called Old Armory Blue (Carbonia) and Dome Blue (Hot Blue).