There are, essentially, two classifications of dyeing residential carpet styles: pre-dyed yarns and post dyed yarns. As the name implies, pre-dyed yarns are dyed before the fiber is tufted into a tufting blanket. Post-dyed yarns are dyed after the tufting blanket is stitched. There are numerous methods of pre-dye and post dye. These descriptions can get much more detailed than the average carpet consumer needs, so we will keep the description very broad. It is not necessary to understand skein dyed, stock dyeing, yarn dyeing, or space dyeing, but it is necessary to understand the differences between pre and post dyeing and the characteristics of each.
All carpet fiber that is to be post dyed is extruded as “white” fiber or fiber that is extruded without color pigment added (see solution dyeing – extrusion). This white fiber is spun, twisted, heat set and tufted into a blanket. After tufting the blanket, dyeing is performed, generally, in one of three fashions, beck dyeing, continuous dyeing and printing.
With heavier products and with polyester fibers, beck dyeing is employed to dye the unbacked blanket also known as greige goods. With this method, the blanket is submerged in a dye bath and the temperature of the dye mixture is raised to open the dye sites of the fiber. The negatively charged dye molecules attach to the positively charged dye sites and the dye adheres to the fiber. This is the most expensive dye method, but is required to get good dye penetration on heavier products.
In products that have been beck-dyed, there may be an excess of dye left in the fabric after dyeing. In rare cases, when you walk across the finished pile with white socks, there may be some transfer to the socks. Also, when cleaning or extracting some of the dye may be found in the extracted rinse water. Neither of these instances should be cause for concern. The dyes are stable and the fiber is not losing color. The dye transfer is simply excess dyes that did not attach to fiber dye sites. This will occur more frequently in deeper shades such as navy blue, hunter green, or chocolate brown.
This is a process in which the tufted blanket dyed on a continuous dye range. This dye method employs spray jets that continuously apply dye to the fiber as the carpet moves underneath. This method of dyeing can produce several hundred feet of dyed carpet per hour and significantly reduces the cost of carpet. The majority of residential carpet is dyed using this dye method. Following, dyeing synthetic latex and secondary backing are applied.
This is similar to continuous dyeing in that printing is a continuous operation. Print dyeing is used to dye all multicolored prints. These are fabrics in which a floral or printed pattern is applied to the surface of the fiber. Many “kitchen” prints and area rugs are made in this fashion, although a number of high style residential fabrics use this technique as well.
Pre-Dyeing refers to all dye methods in which the fiber is dyed before it is tufted into a blanket. While there are numerous methods of pre-dyeing, you should primarily be concerned with the most common method found in residential applications – solution dyeing.
Synthetic fibers begin as fiber pellets, very similar to the pellets found inside Beanie Baby® animals. These pellets are placed in a container, which is heated to the fiber melting point. At the bottom of the container is a device (spinneret), similar to a showerhead, with a number of tiny holes drilled in various shapes. The term spinneret was named after the silk gland used by spiders and silk worms to secret silk. As the pellets melt, they move through the spinneret and the pellets form hair-like strands as they pass through this device. Chilled air is blown across the molten fiber to return the liquid to a solid state. The fiber is then either chopped in short lengths to form staple fibers or left in continuous filaments to form BCF fiber (see staple vs. continuous filament).
Solution dyeing offers a number of advantages and disadvantages to residential carpet constructions. Since color pigment must be mixed in a solid state to dye the fiber during extrusion, color choices are much more limited than with post dyed fibers. However, fiber is dyed throughout rather than on the fiber surface only. Visualize a carrot which has color throughout (solution dyed) as compared to a radish (post dyed) where color is only on the outer edges of the fiber. The advantage is that color, which permeates the fiber, is more difficult to remove as a result of bleaching agents, sunlight, and environmental pollutants.
Contrary to popular belief, solution dyed fibers do not provide increased stain protection and their cost can be significantly greater than post dyed fibers. Unless your new carpet installation will be exposed to bleaching agents or other factors that initiate color fading, there is little need to specify solution dyed fibers. More importantly, since solution dyed fibers are very limited (with the exception of olefin) in the residential market, selection options will be severely limited.
Carpet dye method can affect carpet performance and carpet stain resistance Types of carpet dyeing includes pre-dye, post dye, skein, stock dyeing , yarn dyeing, space dyeing, extrusion dyeing, beck dyeing, continuous dyeing, and print dyeing.