Once the fibers were spun, they could be dyed. Although occasionally fibers were dyed prior to spinning, for the most part dyeing was carried out either on the spun threads or on the finished product,depending on the weaver’s intention. Dyeing is a technique that involves several chemical processes, requiring an understanding of how the dyes and the different types of mordants, needed to “fix” the dyes onto the threads, work. It is easier to dye wool than bast because of the presence of proteins in the hair fibers. The process of dyeing requires sufficient water sources and was done where the biting odors of the dyes and mordants would be least bothersome.The colors used for dyeing were extracted from different elements: from plants such as safflower, indigo, and madder; from animals such as the Murex sea snail, of which broken shell remains discovered in archaeological contexts demonstrate clear evidence of organized retrieval and extraction of the dye substance, and the Kermococcus vermilio a small insect from which kermes was extracted;and from minerals such as ocher and iron derivatives.
The Old Testament mentions three of the most highly coveted dyes used in the cloth made for the construction of the ark of the covenant and the priestly vestments (Exod 25:4; 26:1, 31, 36; 27:16; 28:5, 6, 8, 15, 28, 31, 33; 35:6, 23, 25; 36:11; 38:31; 39:1-3,8, 21, 24, 29): argaman, royal purple, and techelet, a shade of blue, both of which are from the murex snail, and shani, the deep red extracted from the kermes insect. These dyes were renowned through out the ancient Near East for their brightness and steadfastness as they are mentioned as well in Ugaritic and Assyrian texts. Several dyes required a process of fermentation, using a type of ammonia or derivatives of ammonia, to enable the dye to attach itself to the fibers. The mordant, basically salts extracted from metals such as alum, iron, tin, and zinc, was used before or during the coloring process to enable the fibers to absorb the colors.
Evidence for the organized dyeing of cloth in the southern Levant has been found at several sites, the foremost of which is Iron-Age Tell Beit Mirsim. Here, installations of large stone vats bearing grooves and a hole where excess dye material would have been pressed from the fibers and returned to the vat indicate the presence of active dye-works.