The results of this little experiment were actually not bad. Upon opening the container of Coke today I saw two small patches of gunk floating on the surface. These turned out to be directly above the screws, as expected. The bubble plumes mentioned in the previous post were also still present, though they were much smaller.
Once the coke was drained, I realized one mistake I’d made during the experiment. Both of the screws had been placed with the flat side of the head facing downwards, against the bottom of the container. I think this the reason for why the heads are still very rusty, as seen in the photos that follow. In both images the one on the right was the untreated screw.
The things coming out of the Coke weren’t brand new and shiny, but there was a bit of improvement. It’s also possible that leaving them in longer would clean off more rust.