According to the ethnographic study I posted recently, Yom Kippur candles made with threads that had been used to measure graves were usually made in the days between Rosh HaShanah and Yom Kippur, to be lit on Erev Yom Kippur. However, a lot of memoirs and stories describe them as being made on Erev Yom Kippur and then lit afterwards. Last year, I posted an example from Mendele Moykher Sforim's autobiographical novel, Shloyme Reb Khayims, in which he describes his own mother making candles surrounded by a group of pious women. Here is another, very different description of the same ritual, from Y. Y. Trunk's famous memoirs 'Poland.' Whereas Mendele's mother was a good, kosher Jewess, who kept all the mitsvot and read the prayers aloud for the other women in shul, Trunk describes his aunt Royze as a 'folksy Jewish version' of the witches from Macbeth. The difference in the way the ritual is seen may account for the decades between them - both of them witnessed the ritual in their childhoods, and while Mendele was born in 1835, Trunk was born in 1887, by which time such 'mystical practices' were fast disappearing.
One scene with my aunt Royze has become particularly engraved in my memory. It took place one Erev Yom Kippur. At that time, we were already living in the ‘court’ which Grandfather Borekh had built in the middle of a large fruit orchard. Grandmother Khaye had put on the orange silk dress with lace which she wore only on Yom Kippur. As a child, Grandmother Khaye took me with her to Aunt Royze’s hovel. I carried Grandmother Khayes Yom Kippur Makhzor (Prayer book.) Aunt Royze and some other old Jewesses were rolling the big wax Yom Kippur candle. Aunt Royze in her Turkish shall and with the bird on her bonnet was moving heaven and earth. She looked like one of the
witches from Macbeth, but a folksy, Jewish version. All the women, including Grandmother Khaye, were standing around the table crying, wailing and saying tkhines, and Aunt Royze was ominously and relentlessly rolling the yellow yom kippur candle like one rolls a corpse when performing ta’are (ritual purification.) The atmosphere was of the Day of Reckoning, of death of the other world. Aunt Royze didn’t cry, but she continually let out an unhappy and hoarse voice, like an old, angered hen. While this mystic and idolatrous ceremony was taking place, Uncle Avromke lay by the stove, vigorously scratching himself. To this day, I can still see this disturbing and decorative image.
Source: Y. Y. Trunk, Poyln, Vol 2 - Kinderyorn (Childhood) (1946)