8x10 contact prints compared to 4x5 enlargements?

Don't be a wiseacre again, Sal - (I should be ignoring anything you post, and generally do, though you often have interesting and useful things to say). Clear titanium coatings were first developed as a dramatic improvement over brass lacquers for expensive door hardware. I know the story quite well. If something like that turned up SoCal in the early 90's, typically Malibu, we probably shipped it there. That was vac deposited onto complex shapes, but obviously opaque things. I was on the ground floor of marketing that. But we were also one of the largest window dealers in the West, and likewise at least got into the early discussions about the technical issues with optically coating glass windows relative to e-issues. An as an engineer, just like most engineers I've known, you might not be aware that window washing crews don't use optical wipes like for camera lenses, cleaning just a few square inches at a time. The older magnesium coatings like Denglas used weren't realistic for windows, or really ideal for AR picture glass either. And to get a flawless look on a transparent medium with clear titanium imposed a new challenge. And if you were an architect, and not an engineer, I'd probably have to explain that windows are intended to be transparent. They don't teach that in the Architecture Dept here at UCB, perhaps CalPoly. Anytime someone looks out a window at UCB, a brick or bottle gets thrown at them, so they keep the shades closed. Or else one of the peregrine falcons nesting on the Campanile tries to fly in and collides with the glass. We don't want that either.
And if the windows are left open, the falcons will collide with pictures inside and scratch the optical glass, which is expensive to replace.

More to the point: Perfectly even vacuum deposition atop huge flat pieces of glass in high volumes, intended to be cut down afterwards, imposes a very different mechanical and industrial engineering challenge than coating lenses. Go argue with PPG about it, not me. I have enough trouble affording any kind of serious picture glazing these days.