alloy casting in question in crossflow timing cover.

it has a coat of dark grey tranish/oxide that can be sanded off using 400 wet'n'dry but it is quite time consuming.

is there a hosehold chemical that will strip the layer off?

what about grit blasting?

Me I'd use course wire wool etc and some wd40 to get most of the crap off, then autosol and a soft brass rotary brush, followed by autosol and a rotary cloth buff on the drill. Once shiny, wash it very well with white sprit, then several coats of lacquer

I used buffing mpos and soap bars (Buffing compund)
from Shesto.

Linky

My polisher is based on a scrap Garder Shredder with a 1100Watt motor.

Warning!!!
Wear eyeshields, a dust mask, and leather gloves.
It really does the job.
I have used this to take brushed stainless to a mirror polish finish.
I also started with 800 then 1200 grit wet and dry.

Battery Acid will have it off in no time, but watch it, it is quite agressive so a minute or two at most before you rinse it and check progress. You can get battery acid from motor factors for a couple of quid. I did my steering column bearing bracket with it and it came up beutifully in a couple of minutes. The finish is a uniform silver/grey of course. To improve on that you would need to buff it with a polishing wheel.

[Edited on 10/3/09 by sucksqueezebangblow]

one tip alloy will not go shiny is its very cold i love polishing things.

LOL - I am not after mirror finish.

The acid idea sounds good - wold vinegar be effective?

There is raised casting of Fford logo plus some numbers that is hard to get to with wet'n'dry. I could grind that off but .....

Vinegar will take it all off but leave a very mat surface, perfect if you want to then spray it. I use vinegar to clean carbs but you need to occasionally scrub them with a paint brush otherwise they get very minging. With a bit of work they’ll look like new.

Thunderace, I have 8 rims that you very welcome to polish up like those

What about "Wonder Wheels" alloy wheel cleaner ?

I know it's acid based and you have to rinse it off after a few minutes, might be worth a try if you already have some ?