The "Skinny" on Skin
Mezuzot, like Torah scrolls and tefillin, must be written on specially prepared animal hides. Historically, the skins of goats, calves, sheep and even deer have been used. (You can snag an antique deerskin Torah scroll on eBay for just $49k!) Vellum, made from the skins of unborn calves, is prized for its smoothness and pliability. Some also suggest that since it has not entered into our corrupt world nor tasted its pleasures, it symbolizes spiritual innocence and purity. Until recently vellum was a rare commodity, but nowadays, the massive cattle ranges of the American Midwest provide “yippy-ay-oh” choice-grade vellum aplenty for scrolls worldwide. The animal does not need to be kosher slaughtered; it just needs to be from a kosher species.
Of course, the rawhide must be prepared for writing through a tanning process. According to present-day practice, the hides are first soaked in water and then tanned in limewash for a number of days until their hair falls off. They are then hung to dry, soaked again, and stretched on a wooden frame to dry.
A Jew must be physically involved in the process and have intention to dedicate the skins for their holy purpose. The extent of that involvement is a matter of halachic controversy: some authorities allow the use of machinery after a certain point, while others insist that it be purely hand-made. Because of these considerations and others, nowadays sofrim only write on parchment that is produced under rabbinic supervision.
Originally, after the tanning process, the outer hide (epidermis) was split from the inner fleshy skin (dermis) and the revealed surfaces were prepared for their various scribal purposes. This “splitting” is the reason why the Hebrew word for our parchment is klaf (split).
There are three layers of the split 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. Torah scrolls may be written on gvil or klaf, although the use of gvil for Torah scrolls is very uncommon today. Tefillin and mezuzahs are written exclusively on klaf.
Nowadays, for a variety of reasons, the hide is not split. Rather, the soft flesh of the hide is scraped away, and the mezuzah script is written on the epidermis’ inner surface.
The resulting parchment has a non-uniform, grayish surface with natural markings. Unfortunately, a great deal of cheap substandard mezuzot on the market are then “smeared” with glossy white paint to make it easier and quicker to write on them. Aside from the fact that many authorities do not consider such a coated mezuzah surface kosher to begin with, there is also the problem that once the parchment is folded to be put in a case, the coating usually cracks, destroying some of the letters and rendering the mezuzah “non-kosher.” Even if this does not happen immediately, eventually sunlight and humidity will almost surely cause this painted surface to dry and crack.
Not surprisingly, these cheap scrolls are usually written hurriedly and carelessly and do not pass halachic inspection. For these reasons and others it is important to purchase one’s mezuzot and tefillin from a sofer or a reputable merchant. Caveat emptor!
