We learn in the Mishna on our daf that a geṭ may be written with any material: with deyo, with sam, with sikra, with kumus and with kankantum or with anything which is lasting. It may not be written with liquids or with fruit juice or with anything that is not lasting. Furthermore, the geṭ may be written on anything – on an olive leaf or on the horn of an ox if he gives her the ox, or on the hand of a slave if he gives her the slave.
The Gemara defines the terms as follows:
- Deyo as ink;
- Sam as paint – perhaps arsenic trisulfide (As2S3) – a mineral used for coloring and commercial production of ink;
- Sikra as a type of red ink used for a variety of purposes, among them writing and painting. It likely had a lead base such as lead chromate (PbCrO4).
- Kumus as gum, likely resin from a tree like the gum arabic tree (Acacia Arabica or Vachellia nilotica). This type of material is not an ink in and of itself, but a thickener for other ink substances. It is possible, however, that they used colorful resin to write with.
- Kankantum as blacking used by bootmakers, which in English is called bootblack.
The suggestion that the geṭ may be written on an olive leaf stems from the fact that they are hard and have a blank surface that can be written on or carved into. They also remain intact for a long time without changing their appearance. Writing on leaves was not uncommon in the time of the Mishna, although olive leaves were not usually used since they are very small.
While several of the commentaries suggest that the example of an olive leaf is brought specifically because it is long-lasting and the geṭ must remain intact for a certain time, from the Rambam it appears that only the ink needs to be long-lasting, since the Mishna never clearly states the need for long-lasting paper.