We may write [a get] with anything:

with ink,

with red pigment,

with gum,

with iron sulfate,

and with anything that lasts.

We may not write

neither with beverages

nor with fruit juice (from fruits not usually juiced)

nor with anything that does not last.

We may write on anything,

on an olive leaf (that is not attached to the tree),

or on the horn of a cow,

and he must give her the cow,

on the hand of a slave,

and he must give her the slave.

Rabbi Yosi Hagelili says

we do not write

neither on anything that is alive

nor on food.

We do not write on something attached to the ground.

If one wrote (the boilerplate language of the get) on something attached [to the ground],

detached it, and then finished it (with the date and the parties' names),

and gave it to her,

it is valid;

Rabbi Yehuda says it is invalid

until it is written and completed on something detached from the ground.

Rabbi Yehuda ben Beseira says

we do not write neither on [previously] erased paper

nor on unfinished parchment

because it may be forged;

and the sages validate [such materials].