zinc vs cadmium

[bimmerboy]

whats better? all the high grade hardware comes in cad and the cheap stuff in zinc, but ive heard zinc is just as good, and ive heard itll only last a year. whats the deal?

[jerry]

it really comes down to how thick is the coating/plating.

realize that 99% of all chain link fences are coated in zinc. the higher the quality the thicker the coating. hot-dipped galvanized (zinc) bolts will last a very long time and are used in marine environments, such as holding piers together.

unfortunately, what passes for zinc coating is in fact a flash coat and is relatively thin. however, cadmium coatings nowadays are pretty thin too.

when dealing with the thinnes in available coatings, cadmium is considered a bit more durable, but in reality, a lot of these coatings serve to keep the nuts and bolts shiny on the shelf at the hardware store.

if you can get good quality zinc coating, choose it for environmental reasons if nothing else.

[bimmerboy]

(nt)

[02Nut]

Cadmium plating is considered more corrosion resistant than zinc plating. From what I remember, steel parts with Zinc plating will develop "red" corrosion (aka RUST) in about 1/2 the time it takes a steel part with Cadmium plating in salt spray testing.

In real life, I find zinc plating good at preventing red corrosion BUT it tends to develop a "chalky" tarnish (aka white corrosion) that can look really bad.

Cadmium plating also tends to be more expensive because the plater must deal with added Hazmat issues in comparison to zinc plating.

My $.02 worth