Quick feedback on my diamond cut wheel surface issue.
A test of thorough surface rubing using Belgom Alu (an aluminum oxide remover) confirms that there is no clear coat and shows that the oxidation is superficial.
Very effective, but will be time and energy consuming...

 

Daim:


Wow, that process reminds me of "rock polishing". I messed with it at one time. Smaller scale, though. A drum on it side on rollers. Revolved slowly by a small electric motor. Add grit, various choices available .


Very nice stones resulted. I also used it to polish up nuts and bolts
to look better.


Much later, my son made a larger version to use in his machine shop.


Tumblers, that is the term.


I've a spray can on my shelf left over from olden days. A clear coat for "mag" wheels as once known. Obviously, not magnesium, merely
an aluminum alloy.


Some early "Mag" wheel cleaners were mild acids. Care required.
Those big alloy tankers hauling bulk milk and gasoline are cleaned by the acid process. Aircraft as well, I think. or were??? Today's environmental regulations may have ended that.


My car has a very nice set of Lattice XJS sourced wheels. So far, no cleaning issues. Not shiny, merely a clean natural look...probably
cleansed by it's Mr. Clean KIWI PO. A soft media blast.


I messed with bead blasting for a time. Decent set up. Sand for rough work. Glass beads for more delicates. Turned grungy really old Ford
stuff into nice looking parts for my Hot Rod of the 40's project...


Carl

 

Serge,

that surface that you're showing in the pic certainly doesn't look like a diamond-cut surface. I'm pretty sure that Callistos aren't diamond-cut. On diamond-cut wheels, you see all the multiple concentric circles from the cuts.

Your wheels just look like painted / lacquered alloys. Jaguar wouldn't sell a diamond-cut alloy wheel that didn't have a surface coat of lacquer or similar clear-coat as it would just immediately start corroding.

Good luck

Paul

 

Paul, thank you for your enlightening remark.
My mistake, I thought these rims were diamond cut but you are right about the absence of concentric circles.
Going back to the info availbale on these 20" Callisto rims put on the 2006 SV8 Portfolio, I understand that these were indeed only "polished".
Certainly not painted like other Callisto's available later or on other X350's, and I doubt there was any lacquer or clearcoat on these.
That is probably the reason why the surface look deteriorates upon time, as aluminum will progressively coat itself with a microthin layer of alumina that will progressively lead to a dull look.

The more polished is the aluminum surface, the more resilient it will be to oxidation, defects leading to faster corrosion and pitting.
This is also probably the reason why diamond cut aluminum may need clear coating, because of the localised circled grooves on the surface.
Perfectly polished aluminum may be more resilient, explaining maybe the lack of clearcoat on these Callisto's.

Clearcoated aluminum is in principle protected from surface oxidation but may suffer from filamentary oxidation developing under the clearcoat when the clearcoat is not perfect and appropriate oxygen/water ratios become available.

Anyway, food for thought when I recover the original finish, I will have to think of keeping it naked or better put a clearcoat for an easier maintenance and better protection