[sdiy] Finishing Coatings - tips?

[Michael Ruberto]

This weekend I will be focusing on my synths chassis. If you haven't yet 
seen it here's the pic again:

http://frankentron.freezope.org/source/testset2.jpg

After being in the Navy awhile I have gotten quite tired of grey. I've 
decided that I want a rough natural finish. So today I have begun the very 
time consuming job of wire-wheeling the shell, which leaves exactly the 
finish I am looking for. however, I want it to always look this way but I 
know after time the dirt and oxidization will ruin the nice brushed effect. 
Anybody have any tips or suggestions on what I should use to protect this 
finish but preserve the bareness of it?
I thought of clear laquers but I really don't want any unnatural shinyness.

Thanks!

M. A. Ruberto