Are there any real experts here who could comment on this:
Why not just add a matt black layer as the last coating behind the white paint?
From reading through various reports pertaining to the delay. The main one's seem to concentrate on either cohesive or adhesive failure being the problem.
If the white paint is applied to thin the the adhesive shows through but will stick the glass to the phone.
If the white paint is too thick the adhesive won't show through but the paint doesn't have enough internal cohesion to support the stress loads of carrying the the glass, so it falls off.
They seem to be winging that it's getting the paint thickness correct, which is causing the delays.
Adhesive science if a bit of a mine field. And in this one I don't think all of the steps where given sufficient respect. (try walking in to a vehicle paint body shop and suggest they use a silicon based cleaner. I'd say you'll survive about 3 seconds before being launched on to the pavement (sidewalk).
I don't think apple gave full consideration to the type of glass/coating and then to try and paint it????????? NOT GOOD.
Personally I'm not buying any of it, I'd say Apple simply refused to buy a technology package from one of the many specialist coating companies and tried to go it alone, who ever they chose could have pulled a fast one and lied to apple saying it was straight forward and now they've been caught-out.
A technology package like that may have cost $500,000 and a unit price on top. But in the long run it would have worked out a lot cheaper.