Human sweat will damage over time any blueing, case colors or wood finish on firearms....always has, always will....
Human sweat contains numerous minerals, lactate and urea....mineral composition varies with the individual....
Sweat minerals usually contain, in varied amounts, the following trace elements: sodium, potassium, magnesium, calcium, zinc, copper, iron, chromium, nickel, lead and probably many other less abundant trace elements leave the body through sweating with varying lower concentrations.....
Years ago, new Browning and other firearms always contained a hang tag that recommended wiping down a firearm "immediately" after handling to remove fingerprints which damage the finish, they even supplied the gun cloth with each new gun for that purpose.......the above text was the reason......
