According to Jewish law, the tefillin boxes (Batim) should be colored black (Shulchan Aruch, Orach Chayim, 32:40). However, a team of researchers from Israel and Great Britain has conducted a battery of scientific tests that showed that at least some ancient tefillin were not blackened. The research was led by Prof. Yonatan Adler, of Ariel University, together with Dr. Ilit Cohen-Ofri and Dr. Yonah Maor of the Israel Antiquities Authority, Dr. Theresa Emmerich Kamper of the University of Exeter, and Dr. Iddo Pinkas of the Weizmann Institute of Science.
The findings, published tonight in the prestigious journal PLOS ONE (Black surfaces on ancient leather tefillin cases and straps from the Judean Desert: Macroscopic, microscopic and spectroscopic analyses), challenge long-held assumptions about the practice of tefillin observance.
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 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 helped these artifacts survive for millennia until their discovery. Today, the tefillin cases are 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.
“This is a very important discovery,” explained Professor Adler, who led the study. “This is the first time that tefillin have been scientifically examined to determine their color. In some of the ancient tefillin, the leather has a natural brown color. However, in others, the very dark color of the leather was previously thought to be the result of artificial dyeing, which was done to comply with the law that requires the leather of tefillin boxes to be black. Our tests have shown that where the leather appears dark, it is the result of a natural process and not intentional dyeing.”
According to Dr. Ilit Cohen-Ofri, head of the conservation laboratory at the IAA’s 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 boxes were dyed black using either of these methods.”
The researchers used a variety of techniques, including multispectral imaging, Raman spectroscopy, FTIR-ATR, and SEM/EDX, 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 boxes.
“In the dark fragments we examined,” says Dr. Maor of the IAA’s analytical laboratory, “the color appears to be the result of natural leather aging rather than intentional dyeing. 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 ancient tefillin examined in the study were in use.
“It is possible that in the beginning, there was no halakhic significance to the color of tefillin boxes,” explained Professor Adler. “Only at a later period did the rabbis rule that tefillin should be colored black. However, even after this, the halakhic authorities continued to debate whether the requirement to color tefillin cases black was an absolute obligation or merely preferable for aesthetic reasons.”
