"Lou" wrote in message
oups.com...
Ok, but why do I want to coat the aluminum? Is this a process just for
metal planes?
should i be doing this on my aluminum hinges attatched to my wooden
spars?


Aluminum will oxidize if left to it's own means. What the etch - alodine
coat process does is prevent the process form continuing on it's own.

Etch- remove oxidation, and roughen the surface (chemically) to make bonding
of new coatings stronger.

Alodine- actually cause a very uniform thin layer of oxidation to form on
the aluminum, that will help the oxidation from continuing on its own, in
un-uniform ways, possibly up to and including consuming the base metal.
Oxidation on the surface actually protects the metal under it.

Coat- Protects the layer of alodine from wearing away, or continuing on its
own, due to contact to other unlike surfaces, or exposure to the
environment. 2 part epoxies are the best (in some (most) people's opinions)
because it is very resistant to chemicals, moisture, and friction of rubbing
against another surfaces. It also has very good adhesion properties,
allowing it to stick to surfaces and not let go.
--
Jim in NC