The material typically used for the pages was parchment, which is animal skin that's stretched and dried under tension, so it become s really flat and can be written on.

书页通常使用的材料是羊皮纸，羊皮纸是一种动物的皮肤，其在张力的作用下被拉伸和变干，因此它会变得非常平整，并且你可以在上面写字。

youdao

Parchment: a writing material made from goat or sheep skin.

羊皮纸：用山羊皮或绵羊皮造成的书写物料。

youdao

He was of middle age and all skin and bone, as though dark parchment had been stretched over his skeleton without any filling of flesh and blood.

他人到中年，瘦得皮包骨头，仿佛只有一张黑羊皮纸蒙在他的骨架上，里面没有任何血肉的填充。

youdao

The Dead Sea commandments were written in Hebrew on parchment made of animal skin.

FORBES: Ancient Ten Commandments Manuscript On Display

Here, fillets are used and parchment paper, rather than just the fish's skin, provides an extra barrier between the meat and the salt.

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