If tinmen (that apparently are made of iron or steel because they rust) wears
a zinc armour, the armour should take the rusting damage instead of the
tinman when immersed in water.
Also tinmen wearing a zinc armour could get racial adjective 'galvanized' and
get 40% or so acid resist (and the armour would take the damage)
Also a tinmen wearing metal armour that gets hit by a powerful electricity
spell could get welded to the armour and be unable to remove the armour
without taking damage and/or scars.