This video is so helpful that it can use its own thread!
The Codex Sinaiticus: The Oldest Surviving Christian New Testament - The Beauty of Books
Even if you knew nothing else, simply watching this video, and knowing a smidgen about the aging of parchment, how it is subject to oxidation and foxing, should lead to a real consideration that Sinaiticus is simply not an ancient 4th century manuscript that was heavily used for a millennium!
Note the excellent conservation, the ease of leaf turning, (remember Skeat & Milne said that Alexandrinus was limp and dead in comparison) the alive, flexible, supple ms.
Grime from the hands working for centuries on the ms? Naaah..
Note that this is not even the more pristine-in-appearance white parchment Leipzig section.
The Russian scientist Nikolai Alexandrovich Morozov (1854-1946) essentially laughed at the idea that this was passed off as a 1500+ year old heavily used ms. We all can chuckle at how easily the textual establishment was duped by Tischendorf, who pointed the scholars to his smoothed and tampered, deceptive facsimile edition rather than the actual manuscript.
The video gives us a unique look at one of the hidden features of Sinaiticus. Sinaiticus simply is not an ancient manuscript.