Tracking the mysteries of Apple’s supply chain.

It's opening day for the newest incarnation of the iPhone. Already, the faithful are grumbling over the fact that if you want an iPhone 4 in your hands immediately, you'll have to take black. This isn't a Henry Ford, standardizing decision on Apple 's (AAPL) part (the title of the report in the New York Times Bits blog notwithstanding); rather, the company issued a statement explaining that white iPhones are "more challenging to manufacture than expected," which will push their availability into to the middle of next month.

Why would Apple have issues with one color and not the other?

It could be one or a combination of a few things. First is the possibility that Apple was caught by surprise at the demand for white handsets and "manufacturing challenges" is C.Y.A.-speak.

The hiccup could be on the subcontractor side. While most of the component manufacturers are the same for this iteration of the iPhone as for the 3GS—which is available in white—the displays are now being made by LG, which also produces the screens for the iPad. The new iPhone's display is higher-resolution, though, which might be more difficult to produce. LG also produces screens—albeit lower-res than the new iPhone’s —for other smartphones. There haven't been any reported shortages of those components, leading some to finger Apple's demand for a 326 pixels-per-inch screen as the source of the bottleneck.

Even so, why would this affect white iPhones and not their black counterparts? You have to go digging into Apple's (famously secretive) supply-chain logistics. What makes a white iPhone white is just one or two ingredients in a very complicated recipe. The component in question could be sourced from one or more subcontractors, and Apple could use different companies for the white and black parts. If the company making the white piece—probably a much smaller order than the one for the black components—runs into any kind of production slowdown, it could create a shortage. Production redundancies usually guarantee that the consumer remains unaware of any assembly-line scrambles, but again, the relatively small size of the order could play a role here. If Apple was only planning to ship a relatively small number of white iPhones, the scale of its fallback plan might not have been as great, and it wouldn’t slam the brakes on the entire rollout for what’s probably going to be a minority product. (Google searches for “black iPhone 4” are about 10 times more frequent than searches for “white iPhone 4.”)

It's also possible that the color itself is the issue. The iPhone 3GS was dogged by complaints of discoloration, although some claimed the problem wasn’t with the handsets, but with the pigment from aftermarket cases rubbing off. (Discoloration is also a gripe that has cropped up with white MacBooks in the past.) The new iPhone's cover of aluminum-impregnated "Gorilla Glass" could be the culprit. Some speculate the compound doesn’t take to white as well as black as a result of the ion-exchange process that makes the glass resistant to scratches and breakage.