"Chemical dyes" refer to coloring substances that are created or modified using various chemicals. These dyes are used to add color to different materials such as fabrics, hair, or cosmetics. Full definition
They can also produce the wool in ways that don't use chemical dyes, and chemical treatments. (treehugger.com)
There isn't a lot of data on whether or not chemical dyes are safe to use when you're pregnant. (momtricks.com)
In the early part of the 20th Century, chemical dyes began to dominate and, in the opinion of many, to lower the quality of hand - woven rugs. (articles.chicagotribune.com)