The three major stages of tanning a skin to make parchment TB Gittin 22

 One may write a get on anything even a grape leaf, a cow’s horn, and a Canaanite slave’s hand (remember I’m not advocating slavery at all. Just the opposite). We have to understand that a slave was consider property in the eyes of the rabbis. Since the slave was property, the master could write the get on his hand and then give the slave to the wife he is divorcing. Rambam writes: “A get may be written on any substance, even a substance from which one is forbidden to benefit. We may write [a get] on a substance on which an erasure would not be noticed, provided it is given [to the woman] in the presence of witnesses who observe the transfer.

"What is implied? If a get is written on paper with erasures, on parchment that has not been fully processed, on a shard, on leaves, on the arm of a servant or on the horn of a cow, [it is acceptable, provided the husband] gives [his wife] the servant, the cow, the paper, the parchment or the like in the presence of witnesses.” (Mishneh Torah, Sefer Nashim, Laws of Divorce, chapter 4, halakha 2and 3.)

From my understanding, the ex-wife now owns the slave or the cow.

Obviously, parchment is the best material for a scribe to write get upon. Today’s daf TB Gittin 22 distinguishes three major steps in processing the skin of the animal to make it parchment.

“The mishna taught that Rabbi Yehuda ben Beteira says that one may not write a bill of divorce on a material that enables forgery. Consequently, one may not write a bill of divorce on erased paper or on unfinished leather. The Gemara now clarifies what is defined as unfinished leather. Rabbi Ḥiyya bar Ami said in the name of Ulla: There are three hides, i.e., three stages in the process of tanning hides. At each stage, the hide has a different name: Matza, ḥifa, and diftera.

“Matza, as per its plain meaning, with no additives. It is not salted, and not treated with flour, and not treated with gallnuts…

“Ḥifa is hide that is salted, and not treated with flour, and not treated with gallnuts.

“Diftera is hide that is salted, and treated with flour, and not treated with gallnuts….” (Sefaria.org translation)

After soaking the animal skin to remove the meat from it, the skin is then soaked in saltwater and today other chemicals are added to this first stage of tanning the skin. The second stage consists of soaking the skin in water that has flour in it. As the leavening flour helps the tanning process. Soaking the skin in a gallnut solution is the final stage that creates parchment a scribe can write upon.

“A gallnut is produced by oak trees as a defense against parasitic wasps who deposit their eggs in small punctures they make on young branches. The tree excretes a tannin-rich substance that hardens and forms a gallnut. These are collected and ground to be used in dyeing.” (https://www.google.com/search?q=gallnuts&sxsrf=APwXEdcchptmTKgqfbHPyd9fBqPFFRFyEA%3A1686170602675&ei=6uuAZMbNKMqo5NoP7qSCyAk&ved=0ahUKEwjG6rX-grL_AhVKFFkFHW6SAJkQ4dUDCBA&uact=5&oq=gallnuts&gs_lcp=Cgxnd3Mtd2l6LXNlcnAQAzIFCAAQgAQyBQgAEIAEMgUIABCABDIECAAQHjILCAAQHhAPEPEEEAoyCAgAEB4QDxAKMgYIABAeEA8yBggAEAUQHjIGCAAQHhAPMggIABAeEA8QCjoHCCMQigUQJzoECCMQJzoTCC4QigUQsQMQgwEQxwEQ0QMQQzoHCAAQigUQQzoLCAAQgAQQsQMQgwE6BwguEIoFEEM6EAguEIoFELEDEMcBENEDEEM6EQguEIAEELEDEIMBEMcBENEDOg0ILhCKBRDlBBDUAhBDOgoILhCKBRDlBBBDOgoIABCKBRCxAxBDOhEILhCABBCxAxCDARDHARCvAToICAAQgAQQsQM6BQguEIAEOgcIABCABBAKOgoILhCABBDUAhAKOhMILhCABBCXBRDcBBDeBBDfBBgBSgQIQRgAUABYsxVgqRloAHABeACAAY0BiAH7BZIBAzUuM5gBAKABAcABAdoBBggBEAEYFA&sclient=gws-wiz-serp)

Parchment is called klaf in Hebrew.  A scribe will use klaf for writing a Torah, tefillin, and mezzuzot. In all the cases when I acted as a witness for the delivering of the  get, I don’t recall a scribe using klaf. It must be too expensive. The scribe uses heavy stock paper to write a get.