Spring washers feature a split in the washer, and are bent into a helical shape. This causes the washer to apply a spring force between the fasteners head and the fixing material that maintains the washer hard again the material, creating more friction and resistance to rotation.
Galvanised coatings prevent oxidation of the protected metal to create a longer lasting finish. It does this by forming a barrier and by acting as a sacrificial anode if this barrier is damaged. Galvanising is a plating that (in contrast to iron oxide) does not trigger a breakdown of the substrates surface integrity as it is formed. The galvanising, if left intact, can act as a barrier to further oxidation, in a way similar to the protection afforded to aluminum and stainless steels by their oxide layers.