It's common knowledge by now. The original method began in Ancient Egypt, and we can see how the Greeks adopted it, the Romans, and all ancient cultures. How they date the method is by the glue that was used, and later closer to the time of Christ, they sewed it together.
But long story short, ancient cultures took long river reeds (plants) (Papyrus) found in the embankment of the rivers, they would slice them in thin pieces and lay them out to dry, then they would lay the pieces side by side just overlapping the edges where they applied the glue, then they would sit heavy objects on it to keep it flat and from rolling up, then they would double the paper by adding one dried piece on top of another dried piece and glue them together, and within a few days or around a weeks time they would have parchment paper that appeared similar to ancient scrolls.
From the ancient Egyptians, to the time of the Gospels being written, there were 4 distinct differences (just slightly different) how the paper was made and glued/later sewn together. And this is how they can date ancient manuscripts based upon the papyrus method.
Papyrus Definition and Meaning - Bible Dictionary
Papyrus Definition and Meaning - Bible Dictionary
1. Papyrus Paper:
Most importantly, from it was made the tough and inexpensive paper which was used from very ancient times in Egypt and which became the common writing-material of the ancient world. The white cellular pith of the long triangular papyrus stalk was stripped of its bark or rind and sliced into thin strips. Two layers of these strips were laid at right angles to each other, pasted together (Pliny says with the aid of Nile water), dried and smoothed. The sheets thus formed were pasted one to another to form a roll of any length desired. The process and the product are described by Pliny the EIder (NH,.xiii.11-13).
I will provide some dates that experts, understanding these methods, have dated biblical material.
***Remember the letter P before the number (P4) stands for Papyrus***
The Matthew fragments redated by Thiede are at Magdalen College (Oxford). They are called The Magdalen Papyrus (listed as Greek 17 and
p64)
date the fragments to around A.D. 48 to 69.
Because of the reference to the destruction of the Temple in Jerusalem in 70 CE (Mark 13:2), most scholars believe that the Gospel of Mark based upon a fragment of papyrus from
Qumran,
was written some time during the war between Rome and the Jews (66-74). Most early dates fall around 65 CE.
Acts was written in 62/63 or before, then Luke was, of necessity, written before Acts (say 60–61 AD).
P46 is dated to around
65-100 A.D. and contains Paul’s epistles.
Based on a variety of evidences including papyrus, the Gospel of John is considered a later writing due to the differences of the other 3 Gospels, and the specific divinity content of Jesus as God.
Collectively, it has been suggested to be a post-90 AD composition.
Anyway, that is some examples and ages dated by the papyrus method...