Melacha #30 [29]: M'SARTEIT - SCRATCHING OUT (MARKING)

Av Melacha: Scoring an animal hide in order to cut it to a specific size.

Principle: Marking an object to facilitate folding, cutting, or writing.

Toldot: Scoring lines, or folding a material to find its center.

It is therefore prohibited to make a mark on a napkin or paper, in order to later fold it on that spot.

This Melacha does not apply to food. Therefore, it is permitted to mark challah with a knife before HaMotzi.

Melacha #31: M'CHATEICH - CUTTING [TO SIZE]

Av Melacha: Cutting an animal skin to size.

Principle: Cutting an object to a specific size or shape.

Toldah: See examples below in the Chayav section.

1. Chayav: Cutting a roll of bandages, separating garbage or sandwich bags from a roll, cutting plastic to cover tables, tearing toilet paper, or removing from a package tissues which are not completely detached.

2. Exception: The Rabbis declared that if human dignity is at stake, one may break this prohibition using a Shinui (change). Therefore, if one does not have torn toilet paper, and nothing else is available (e.g. loose tissues), it is permitted to randomly tear the toilet paper with a change (e.g. using your elbows), and preferably not on the perforation line.

3. Patur aval Assur: Tearing paper, plastic, or any other material where there is no beneficial result in the tearing itself.

4. Mutar: Cutting or tearing food, because this Melacha does not apply to food. For example, bread may be sliced to a specific size.