Design creation or selection involves consideration of the range or limitations of the various methods of carpet manufacture. The number of colours that can be used for Jacquard Wilton and gripper Axminster are limited; spool and chenille Axminster allow unlimited colour range. Density tends to be greatest for Wilton carpet, sometimes reaching as high as 130 per square inch.

Spool Axminster designs are made from a chain of spools, with one spool to each row of pile. There are usually seven threads to the inch across the width, with a pile yarn length per thread of about 35 feet (11 metres). Spool width varies according to the loom, the smallest is usually 18 inches (46 centimetres) wide. The person operating the machine creels all necessary colours for the tufts in a row and winds the full spool, repeating the process until the full set for the design is made.

Gripper Axminster and Wilton Jacquard looms utilize a perforated card system to select the required combination of different coloured threads per row of pile. There is one card per row, punched according to the predetermined design, and the possible colour choice for each tuft is usually one in five for Wilton and one in eight for gripper Axminster. “Planting” of several additional colours in the pile-yarn creel may increase the number of different colours possible in a design. High- and low-cut and uncut effects are also possible in Wilton carpets. Normally employed on tufted carpets, the process can be applied to all types. Different pile height effects are produced in tufted carpets by using different rates of yarn feed, and are sometimes emphasized by alternating the colours and hiding the colour of low pile under adjacent high pile. Mechanical and photoelectric devices are used to regulate the rate of yarn feed to the tufting needles.

Construction

The basic structure of traditionally manufactured carpets consists of the backing fabric and the pile, which is bound under and between the weft. Pile is formed on Axminster looms by inserting weft, with reciprocating needles, across the warp chain yarns. A central stuffer warp usually separates top from bottom weft. In Jacquard Wilton and Brussels carpet, the pile not used for surface design effect is concealed between top and bottom weft; Axminster carpet uses all pile yarn for surface effect. Wilton pile is formed by looping the yarn over wires that project it mechanically across the width of the loom and beneath the decorative pile yarns. When the wires are withdrawn, they either cut the pile, forming Wilton, or leave it uncut to form Brussels carpet.

In spool Axminster carpets each row of tufts is inserted and cut away from the spools. On gripper Axminster looms each tuft is inserted by its individual beaklike gripper, after being cut away from the carrier. Backing fabrics have warps held on flanged beams; in Wilton weaving, weft threads wound on cops are shuttled across the loom. Axminster weft is drawn from large stationary cones at the side of the loom.

Tufted carpets differ basically from traditional types because they have a prewoven backing into which the tufts are inserted. One unconventional method of making carpet involves the forming of pile on knitted structures. Another method involves the application of pile yarns or even undulating webs of fibres to backing fabric by means of adhesives. These methods often lack the means for controlling design.

Finishing

After weaving, carpeting may require machine brushing to remove loose fibre or yarn, before any correction of processing faults. Traditional carpets have a separate reparation process, but on tufted carpets, missing pile, the most common fault, is stitched in by a portable “gun” operating a reciprocating needle. The carpet pile is then sheared to uniform level with cutting blades similar to those of a wide lawn mower. Steaming of the pile causes it to expand or “burst” into an aesthetically enhanced state. Natural back-sizings were formerly applied to Axminster carpets, and Wilton and Brussels weft threads on their cops were soaked in sizing. Increasing use of such synthetic backing compounds as polyvinylacetate and different kinds of lattice backings now produces excellent tuft bind and stiffness.

Other modern finishing processes include mothproofing of wool, often performed in the dyeing sequence, and application of soil-resistant finishes to man-made pile, rot-proofing, and antistatic treatment.

Reinforcement or screening, particularly used for tufted backing, may employ adhesives on open structure woven materials, and the use of such cushioning materials as synthetic rubber foam is increasing.