Update | The Galaxy Z Flip may be more fragile than Samsung would like you to think
Update: During his Motorola Razr 2020 teardown video, JerryRigEverything's Zach Nelson addressed fan observations that the Galaxy Z Flip does in fact have a layer of fibers running along the entirety of the hinge internally, thus matching its promo images more closely. Therefore, those who bought this new foldable phone may now feel slightly better about giving Samsung their money. These components' performance in everyday dust-exclusion remains to be seen, however.
The excitement felt by potential Samsung Galaxy Fold customers at the launch of this ground-breaking foldable phone may have been matched by anxiety raised by subsequent reports asserting that grit and dust were more than capable of invading it. This issue was particularly prevalent around the hinge area of the device, and could mar the flexible display's appearance or functionality.
Samsung sought to address these concerns by engineering additional reinforcements around these points on the Fold when it was re-launched on the market following an overhaul of its design. Furthermore, it asserted that it had put even more work into its follow-up product, the Galaxy Z Flip. The most notable part of this process was the inclusion of "fibers" portrayed as running the length of this nouveau clamshell's own hinge in order to keep this component free of potentially harmful particles.
However, when iFixit went to test this marketing claim out, it appeared to fall on its face more than a bit. For a start, the YouTubers showed that this "dust-excluder" is only present at either end of the hinge on the Z Flip's teardown, a finding replicated during JerryRigEverything's dissembly of the same.
Furthermore, the former channel demonstrated the lack of efficacy of these "brushes" against exposure to flourescent purple powder. This hi-vis dust, with which the phone was treated prior to its teardown, also found its way into other parts of the phone such as the internals near its charging port. Therefore, this seems a total fail for the Z Flip's ingress-protection (well, as far as fine UV-reactive stuff goes, anyway).
In slightly more encouraging news, JerryRigEverything's host Zach Nelson was also able to conclude that the same phone does in fact incorporate ultra-thin glass. This was confirmed during an attempt to partially deconstruct the various layers of the Z Flip's display. On the other hand, the same material turned into tiny fragments during this process, which may reduce confidence in its durability. Oh well...at least it's not plastic.