The general MacRumor user cracks me up
Part of the problem with the comments on this forum is people generally have no idea what they're talking about. When it comes to anodise it seems like people really do have no idea.
Before you reply about my comments please take a look at the products my company designs and manufactures:
http://www.360precision.com
In any given year we have thousands of individual components hard anodised. What may seem like a simple process is far from it. There are dozens of variables that need to be EXACT to achieve a consistent colour and finish. I don't know the precise science behind the process but I know enough to provide an intelligent comment regarding the iPhone issues.
My first comment is on the photo on the first page, these types of marks are not actually scratches IN the anodise but transference from a less hard material. In this photo they've not actually removed the anodise from the iPhone but left behind material from the key on the surface. These marks can either but rubbed off or polished out. Yes, type III hard anodise is actually HARDER than the material car keys are made from.
Second comment is regarding the scuffs and general appearance of the finish. With aluminium you will always need some type of surface treatment BEFORE the anodise process to remove either machine marks or markings from other manufacturing processes. With any of these processes unless you have the parts highly polished the aluminium will always have a slight texturing, couple that with the hard finish of the anodise and you end up with a very fine like sandpaper effect.
We tried a sand blast finish on a batch of our parts and even after general handling during assembly the parts looked scuffed. Basically you end up with the part covered in dead skin cells and oils from the skin. So unless the iPhone backing was shinny like the chamfered edge you're always going to end up with a part that picks up marks from your hands and other materials it comes into contact with. They will however clean off.
As I don't have an iPhone 5 I can't actually test to see the actual spec of anodise used. But from looking at the colour and the fact that Apple needs an absolute colour and finish match between all iPhones I find it hard to believe that it is in-fact type III but more like type II anodise. Although type II is hard, it's nowhere near as durable as type III.
With type III anodise it's extremely difficult to guarantee an extreme colour match between batches of material. With aluminium you will always have variation of the alloy composition even within the the same spec. Slight changes in the copper or silicon content can have an effect on the shade of black you can achieve when the parts are anodised. The last thing Apple would want is some parts really black and others dark grey.
Also due to the thickness of the part it would be difficult to type III anodise without actually burning or pitting the part. The minimum thickness for type III hard anodise is 25 microns, so you have 12.5 micron growth INTO the part and an additional 12.5 micron growth ON the apart. Type I or II on the other hand can be much thinner making the process far easier.
The other factor is environmental. Type III anodise produces a lot of toxic by products that need to be disposed of and I can't see this process fitting in with Apple's environmental policy.
I could of course be wrong and until I have an iPhone 5 and can measure the actual thickness I can only speculate.
What I can say though is that unless you're actually GOUGING the back plate almost ALL scuffs and scratches should either rub off or in extreme chases be polished out using a t-cut type polish.
Matt
