4.1 Portability
Flexible sheets reduce weight dramatically compared with stone or equivalent volumes of clay.
4.2 Extended text
Sheets can be joined into rolls or folded into gatherings, supporting long narrative, legal, religious and scholarly works.
4.3 Two material ecologies
Papyrus depends on plant geography and trade; parchment depends on livestock, skin preparation and skilled labour.
4.4 Surface behaviour
Fibre direction, hair/flesh sides, sizing and polishing influence ink, script and page planning.
4.5 Reuse
Both materials could be written on again. Parchment palimpsests and reused papyrus demonstrate economic pressure and layered information histories.
4.6 Climate-sensitive survival
Organic media preserve unevenly. Dry environments privilege papyrus evidence, while damp conditions destroy much that once circulated.
4.7 Format transition
Papyrus was strongly associated with the roll but also used in codices. Parchment became especially compatible with folded gatherings and durable bindings.
4.8 Biological and material evidence
Parchment can preserve traces of animal species and production; papyrus structure can reveal manufacture, repair and reuse.