For my VTG Steam irons plate I do so:
For my VTG aluminum steam irons I always used soap pads , if you got alu oxydation there is nothing that can let it go than removing it manually by rubbing with metallic pads, and do not use descaler or stuff like that they will oxydate the plate further as they're acids, so with a soap pads will remove all the oxydation on the plate, of course will produce some fine and thin "scratches" the same you see on used irons regularly used and cleaned.
All I do is: Take a warm water bowl and dip in it the soap pads and rub vigotously on a sink or towel in all the plate with iron in vertical position not upward or the scum will get into holes, you'll get metallic grey dark foam and scum and see the plate progressively get more brilliant and whiter, that is the patina of oxydation that you're removing...
Once you're done rinse it with a wet cloth until the dark patina you'll get on the cloth will be gone and so stopped to be left and you'll have a cleaned plate.
I also rinse internally with a solution of 1/3 vinegar and rest water and shake and let drop water from the holes with iron warm, then repeat the procedure with plain water for about 2 or 3 times...
P.S Just to clear any possible doubt that may occur:
Clothes and towels stained with grey oxydation residue will get clean with a simple hot wash.
[this post was last edited: 12/28/2012-17:05]