There are four melakhot that relate to preparing animal skins for writing: Mafshit, Me’abed, Memaĥek, and Mesartet (as explained below). When parchment was the standard writing surface, everyday things were written on it. Nowadays, however, only Torah scrolls, tefilin, and mezuzot are written on parchment. Additionally, nowadays, animal skins are used to make leather clothing, shoes, satchels, and upholstery. In the Mishkan, skins were prepared to be used as curtains as well. Mesartet was performed not only on skins, but on wood as well – to designate a place on the boards for writing.
Mafshit refers to removing the skin from an animal that was slaughtered. This skin has two layers. The outer layer, or klaf, is the material upon which Torah scrolls, tefilin, and mezuzot are written. The inner layer, or dokhsostos, may only be used for mezuzot. One who separates the two layers transgresses a tolada of Mafshit. Although one may not remove an animal’s skin, one may skin a cooked chicken, because the prohibition of Mafshit does not apply to edible meat.
Me’abed refers to placing the skin in salt, lime, or other substances that draw out the skin’s juices and acids. This allows the skin to last for hundreds of years. Any action that prepares skins for use is included in this melakha. Therefore, one may not to stomp on skins to harden them, use one’s hands to soften them, or spread oil on them to make them soft and pliant (MT 11:6). We explained above the laws of Me’abed as they pertain to food (12:9).
Memaĥek refers to smoothing the skins by removing hairs and irregularities. This melakha also includes smoothing any rough surface, such as wood or stone, by means of sandpaper or a file (Shabbat 75b). It is also forbidden to scour silver items with a material that smooths their surface (SA 323:9). One may not scour metal with steel wool or sharpen knives (MB 323:40).
The melakha of Memaĥek has a tolada called Memare’aĥ, which refers both to spreading a substance evenly upon an object and to spreading a substance on an object in order to smooth out the object. Therefore, one who spreads ointment on a poultice transgresses Torah law (Shabbat 75b; see below 28:8). It is also forbidden to spread lotions and creams on one’s body, as explained above (14:5). Similarly, one may not polish shoes by spreading cream on them. Even without a cream, one may not rub leather shoes in order to shine them (see AHS 327:4; SSK 15:40). As we explained above (12:11), according to most poskim, the prohibition of Memaĥek does not apply to foods.
Mesartet refers to scoring a line to facilitate writing in a straight line. This melakha also includes drawing a straight line on leather, wood, or stone in order to mark where to cut these materials. However, one may use a knife to draw lines on a cake or to score an orange, to help one cut with precision. Since the prohibition of Meĥatekh does not apply to food (as explained above in 15:10), Mesartet does not apply to food either (MB 322:12, 18; SSK 11:15).