The av melachah of mesarteit refers to ruling or etching lines on any material in order to accurately cut along or write on them.1

Mesarteit in the Mishkan

The hides used to cover the Mishkan first underwent a thorough cleaning and tanning process to make them fit for use. Afterward, they were measured, cut to size, and attached to one another to cover the entirety of the structure. To ensure the pieces were accurately sized, lines were drawn on the leather to indicate exactly where they should be cut. The ruling of these lines is the source for the melachah of mesarteit2 and the cutting is the source for mechateich.3

Common Activities to Avoid

  • Tracing a picture from a coloring book.
  • The parchment used for Torah scrolls, mezuzot and tefillin are etched with lines to guide the sofer (scribe). These lines may not be made on Shabbat.
  • Using a ruler to rule lines across a piece of unlined paper.