On Mon, 11 Jul 2005 08:55:14 -0700, "RST Engineering"
wrote:

I prefer not to anodize anything on the airplane. Anodizing forms a VERY
hard insulating film that you have to spot-face down to the aluminum to make
an electrical connection. I prefer to powder coat, which is nearly as tough
under operating conditions but not nearly as difficult to get an electrical
connection.

Jim

Another point against anodizing is that it increases the notch
sensitivity of already notch sensitive aluminum. This is far more
significant with hard anodizing than with decorative, but that
aluminum oxide will crack then concentrate the stress in the crack.

Powder coat has its problems too, and they are aluminum grade, product
and process dependent. All the processes I know actually "melt" a
powder on the surface. The temperatures of some powder processes are
above safe operating (change of properties) temperatures of some heat
treated aluminum alloys. I use "some" because I don't know details.

The best way is to get the whole panel laser cut and then anodized black
after test fitting the instruments.

George