Anodized interior aluminum

[ebb]

Powder coating is a relatively permanent coating available in any color and is usually a polyester. The aluminum is charged, the powder is blown on and adhers evenly and then it is melted in an oven. What is great about it is that is is a nontoxic process with no fumes or solvents.
The transformation can be rather startling as it was for me with 338's window frames.
While powder coating is a newer process, it has been around for 40 years or so.
Think there have been many variations of methods and materials in A/C's, so what is "original' may be what was available at the time when the boat was assembled.