Can one use a regular black pen to write a mezuzah? or even use regular black ink to write a mezuzah? If not, Why?
Thank you so much.
While the pen itself is ok, and the use of a quill is mainly because we want to maintain the tradition as it has been throughout the generations. The ingredients of the ink pose a bigger issue. The Talmud in Shabbos 103 tells us that a Sefer Torah [and mezuzahs and other Sta”m articles] must be written with “dyo” literally ink. There is a vast discussion in the Talmud and commentaries as to what this “dyo” must be made of. The various opinions are codified in Shulchan Aruch Y:D 271, O:C 32:3, see the Mishan Brura and Biur Halacha for a summary of the halachic conclusion. Hence the ink must be made following these guidelines, and the average ink may not qualify.