When you have something engraved in a traditional way, with a spinning cutter that looks vaguely like a tiny end mill or countersink, there remains a clearly defined cavity of consistent depth, that is fairly easy to fill with paint. Laser engraving leaves a tiny crater, or rather some neat arrays of very tiny craters. The craters don't have the sort of surface recommended for good paint adhesion, and I don't know of anyone who claims ability to do so.
UV can be used to hasten the cure of some kinds of paints and inks. I'm not familiar with it.
You could screen the image of the decal on, in ordinary ink, or in epoxy ink, with a clear over coat.
I'm guessing the aluminum oxide coating to which you refer is an anodized finish, which comprises electrochemically converting the actual surface of a very clean aluminum part to aluminum oxide. The oxide ends up microcracked, so there will be corrosion in the cracks unless a coat of sealer is applied. The sealer is often dyed some attractive color, both for cosmetic reasons, and to provide proof that the anodizing has been done and the sealant has been applied. There are some outfits that can reproduce graphics, like labels, in the sealer coat.
You cannot anodize over dirt, or sealant, or paint, or labels, or fingerprints.
Mike Halloran
Pembroke Pines, FL, USA
