A mezuza can be of varying degrees of quality, dependent on several factors: the quality of the parchment, the beauty of the writing, and the personal attributes of the scribe who wrote it. The scribe must meticulously write each letter by hand according to its precise requirements. As this is easier to do when the size of the parchment and letters is larger, small mezuzot are usually of poorer quality than large ones. It is possible, however, for a small mezuza to be written with great precision, and in that case it will in fact generally be more expensive than a large mezuza, as its writing requires more painstaking effort to achieve the same level of accuracy.

The mezuza parchment must be made from the skin of a kosher animal, which has been tanned and processed with special intent to be used for the mitzva of mezuza. There are various levels with regard to the quality of the parchment. Some manufacturers coat the parchment with white lime wash, which facilitates writing on its surface. However, the lime makes the mezuza more susceptible to damage from moisture and deterioration over time. Furthermore, the lime can crack, which may cause damage to the letters. Therefore, one should avoid buying such mezuzot.

It is important to keep in mind that a mezuza printed on paper, even if the paper closely resembles parchment, is not valid for the mitzva. This is not a mezuza at all, and the residents of a house with such a mezuza do not fulfill the mitzva. Unfortunately, some distributors sell forgeries of this kind, and this is another reason to buy mezuzot only from a reliable vendor. The best way to obtain kosher mezuzot of superior quality is to buy them from a God-fearing scribe, with whom one is familiar and who is trustworthy, or from a store run by reliable, God-fearing people.

The mezuza is written by a scribe, known as a sofer Stam, “a writer of Stam,” Stam being an acronym for sifrei Torah (Torah scrolls), tefillin (phylacteries), and mezuzot. This is a professional scribe who has studied this special art of writing, along with its halakhot, and is qualified to perform this holy task.

The scribe must be a trustworthy, God-fearing man. The fulfillment of the many halakhot of writing a mezuza depends on his integrity; since some of them depend on the intent of the scribe, no one else can know if he was in truth stringent about them and had the proper intent in mind.

The mezuza is written with a feather quill. Special black ink is used; the ink is made by a process that must also meet the requirements of a series of halakhot.

Further reading: For an interesting explanation on why a mezuza must be written with a quill, see A Concise Guide to the Sages, p. 361.

The completed mezuza is rolled up (preferably by an expert) from the end to the beginning, with the writing on the inside. Then it is wrapped, usually in plastic wrap, to guard it from weather damage, and placed in a protective case. The mezuza case has no halakhic significance, and therefore there are no rules about the material from which it may be made, or its shape. However, if a mezuza is affixed to the doorpost in a room where a married couple sleeps (and the door is on the outside of the doorpost), it should be in an opaque rather than a transparent case.

Two important points should be borne in mind:

(1) The mezuza case is merely an external covering, and at most it may be said to be an embellishment of the mitzva, but it is not the main mitzva object. The greater investment of one’s money should be focused on the quality of the mezuza parchment.

(2) Some people mistakenly place the rolled parchment facing downward, which means that the mezuza is upside down. The mezuza must be affixed to the doorpost with the writing facing upward. An inverted mezuza is not valid and it is as if it is not there at all. If a mezuza was affixed upside down, it must be reset in the correct position.