Ancient tefillin, or phylacteries, were not colored black, as is mandated by contemporary Jewish law, a scientific study has found.

The discovery challenges long-held assumptions about the practice of tefillin observance.

The research, which was published in the prestigious journal PLOS ONE, is the work of a team from Israel and Great Britain. A battery of scientific tests showed that two-millennia-old tefillin uncovered in the Holy Land were likely the color of their natural leather when they were in use.

Tefillin are small leather cases containing minuscule parchment scrolls inscribed with biblical verses. They are worn by observant Jewish men and some liberal women as part of their weekday morning prayers, one on the head and one on the arm.

“This is a very important discovery,” said Professor Yonatan Adler of Ariel University, who led the study. “This is the first time that [ancient] tefillin have been scientifically examined to determine their color.”

He noted that in some of the tefillin, the leather has a natural brown color. In others, however, the very dark color of the leather, which was previously thought to be the result of dyeing, was in fact natural.

“Our tests have shown that where the leather appears dark, it is the result of a natural process and not intentional dyeing,” he said.

Ancient tefillin in a cave

Back in 1949, archaeologists discovered several leather tefillin cases in a cave near Qumran, where the first Dead Sea Scrolls were found. Subsequently, additional tefillin cases were unearthed in other caves near Qumran, in Wadi Murabba‘at and in Nahal Se’elim—all in the Judean Desert.

These findings are dated to the same time as the Dead Sea Scrolls, from around the end of the Second Temple period—or about 2,000 years ago.

The arid desert climate allowed these artifacts to survive for millennia until their discovery, and the tefillin cases have been preserved in the storeroom of the Israel Antiquities Authority’s Dead Sea Scrolls Unit in Jerusalem, where the climatic conditions of the caves are replicated.

According to Dr. Ilit Cohen-Ofri, head of the conservation laboratory at the Dead Sea Scrolls Unit: “In ancient times, there were two main methods for dyeing leather black. The first method used carbon-based materials—soot or charcoal—to give the leather a black color. The second method was based on a chemical reaction between tannin, a complex organic compound found in many plants, and iron oxides. In our tests, we ruled out the possibility that the tefillin cases were dyed black using either of these methods.”

The researchers used a variety of techniques, including multispectral imaging, to examine the leather of the tefillin cases for traces of black dye or paint. The results of the analyses showed no evidence of black colorants on any of the tefillin cases.

“In the dark fragments we examined, the color appears to be the result of natural leather aging rather than intentional dyeing,” said Dr. Yonah Maor of the Israel Antiquities Authority’s analytical laboratory. “Minor water leakage into the caves over the 2,000 years the artifacts have been there could have accelerated the leather aging process. In the past, we have found that some of the Dead Sea Scrolls have also undergone a similar process, which unfortunately has caused the parchment to darken.”

The researchers believe that the practice of coloring tefillin cases black is likely due to a later tradition. They suggest that the law requiring tefillin to be made black may not have been in place in the Second Temple period, when the tefillin examined in the study were in use.

“It is likely that in the beginning, there was no halachic significance to the color of tefillin,” explained Adler. “Only at a later period did the rabbis rule that tefillin should be colored black.”

As the centuries passed, Jewish religious authorities continued to debate whether the requirement to color tefillin cases black was an absolute obligation or merely preferable for aesthetic reasons.

“It is commonly thought that Jewish law is static and does not develop. Our ongoing research on ancient tefillin shows that the exact opposite is true; Jewish law has always been dynamic. In my view, it is this vibrancy that makes halachah so beautiful.”

Photos Courtesy of Israel Antiquities Authority