The Parchment

The parchment is called klaf. It is made from the hide of a kosher animal species. There are 3 layers of the hide. The top layer just below the hair is called gvil. The layer beneath is called klaf and the lowest layer, against the flesh, is called duchsustus. Torahs may be written on gvil or klaf. Tefillin and mezuzahs are written exclusively on klaf. The use of gvil today is very uncommon. Today, most klaf is made from the hides of calves as it makes the finest parchment..

The hides are soaked in water in preparation for tanning. They are tanned in lime wash for a number of days until the hairs fall off. They are then hung to dry, resoaked and stretched on a wooden frame and dried. At this point they are sanded to an even, velvety smooth surface, ready to be written on.

The tanning process must be done with specific intention for the holiness of Torah, tefillin and mezuzah. The tanner does this by uttering  at the outset of the tanning process "Lshem kedushas sefer Torah, tefillin u'mezuzah" -- "For the sake of the sanctity of a Torah scroll, tefillin, or mezuzah."

Before the sofer can write on the klaf, straight lines, or sirtutim, must be manually scored with an awl along where the letters will be written. In addition lines are scored along the right and left margins.

Some scribes have adopted the practice of coating the top surface of the parchment with white lime wash. This makes the parchment easier to write on and allows the sofer to write more quickly, lowering the cost. However, there is an halachic issue as to whether such a coating is acceptable. The sofer must write on parchment, not on paint, and most Rabbinic authorities strongly discourage or even forbid the use of coated parchment, for even were it to be initially acceptable, the coating has a tendency to crack, which breaks the letters and invalidates the scroll, making it very quickly not kosher.

Some older Torahs have a coating on the backside. This was done to beautify the parchment and likely to cover up various blemishes. This adds significant weight to the Torah scroll and leaves residue on the letters, giving them a false gray appearance. There is no halachic concern other than the coating concealing patches. Parts of letters may not be written on a patch.