Oh Yes You Can

Decide

that Galvanic Corrosion

is Boring

or maybe not...

This is a test to see what would happen when 3 different metals are in contact with 2 different metals while in tap water and salted tap water for 14 years.

The first test put a zinc plated screw, a brass screw and a stainless steel screw into copper flashing and into aluminum flashing while in tap water for 14 years.

The second test put a zinc plated screw, a brass screw and a stainless steel screw into copper flashing and into aluminum flashing while in tap water with ADDED SALT for 14 years.

Here are the results:

This is the test that was immersed in tap water.

Left to right the screws are brass, zinc plated and stainless steel.

The top shows screws in copper flashing.

The bottom shows screws in aluminum flashing.

This is the test that was immersed in tap water plus salt.

Top to bottom the screws are stainless steel, zinc and brass in aluminum flashing.

Please note the 2 holes in the aluminum flashing that are not present with only tap water.

This is the test that was immersed in tap water plus salt.

Top to bottom the screws are stainless steel, brass and zinc in copper flashing.

Please note the large deposit on the bottom of the zinc plated screw and the large deposit around the top edge of the brass screw.

If you look up Galvanic Series on the Wikipedia it gives a list of metals that are anodic and cathodic.

The further apart the metals are on the scale the more galvanic corrosion should be expected.

So stainless steel screws in aluminum flashing would be expected to show the most corrosion.