Knot Density: Refers to the number of knots per square inch or square decimeter in a handmade rug.Rug density measured in the imperial system in square inches and in the metric system in square decimeters.KPSI is sometimes used to indicate value and a higher the number of knots per square inch, the higher the quality, and price.
Dyes/Dying: Aprocess of changing the natural color of materials such as wool, silk and cotton. There are two types of dyes: natural dyes and synthetic dyes:
Natural Dyes: Natural dyes only used until late 19th century. Natural dyes include plant dyes, animal dyes and mineral dyes. Plant dyes come from roots, flowers, leaves, fruit, and the bark of plantswoad, (plant of the mustard family and indigo.
- Blue dye is taken from a bush from the pea family.
- Yellow dye is produced from saffron, safflower, sumac, turmeric, onionskin, rhubarb, weld, and fustic.
- Red and Brown dyes are produced from Madder, Redwood and Brazil wood has been used since ancient times for
- Black dye comes from catechu dye, oak bark, oak galls, acorn husks, tea, and walnut husks.
- Organe is produced from Henn
- Green comes from indigo, over-dyed with any of a variety of yellow dyes
- Mineral dyes come from ocher (yellow, brown, red), limestone or lime (white), manganese (black), cinnabar and lead oxide (red), azurite and lapis lazuli (blue), and malachite (green)
Synthetic Dyes: Are in use since the mid-19th century, when demand for handmade rugs increased in the West and production increased in the East. A need for easy-to-use and less expensive dyes with a wider range of colors drove a wave of a development of synthetic dyes in Europe. Synthetic dyes were then imported to Persia (Iran), Anatolia (Turkey) and other Eastern countries. The first synthetic dye, Fuchsine (a magenta aniline), was developed in the 1850s and other synthetic aniline dyes followed, later banned by the Persian king. Persian weavers discontinued the use of synthetic dyes until the modern synthetic chrome dyes developed between World Wars I and II. Chrome dyes are colorfast, retain their intensity and are produced in a variety of attractive colors and shades.