Decorative Techniques

Fabrics usually need to be washed, bleached and dyed before they are made into textile products. Garments are assembled using various joining techniques including sewing, fusing and heat-sealing. Finishing improves the appearance, handle and performance of fabrics, while pressing is used to shape and stabilise fabrics.

Dyeing and Printing

Before dyeing and printing the fabric is prepared by washing, bleaching and mercerising, in which the yarn is treated to improve strength, lustre and receptivity to dye. Fabrics can be dyed by hand or by machine.

Hand dyeing

In hand dyeing, fabrics are immersed in hot or cold dyes in a dye bath. The dye bath is agitated so the dye reaches all areas. When the desired colour is achieved the fabric is removed and rinsed to remove excess dye. Then it is fixed with a mordant or a fixing agent such as salt. The strength of a dye colour is determined by the:

• amount of time in the dye bath
• absorbency of fibres
• original fabric colour
• concentration of the dye colour in the dye bath
• effective use of a mordant or fixative

Commercial dyeing- In industrial production fabric is dyed by continuous or batch dyeing.

Continuous dyeing -The fabric is passed through a dye bath, and then squeezed between rollers to spread the dye evenly and remove excess. Continuous dyeing is used for colours that do not need to change too quickly with fashion.

Batch dyeing -Fabrics are produced without dye. Instead, they are dyed to order in large batches according to the colours required. Batch dyeing is used for fabrics that have to change in colour frequently because of fashion.

Printing -Fabrics is printed by block or screen printing.

Block printing - Block printing is done using metal or wooden blocks, one for each colour. The background shapes are cut away to leave a raised design on the block. Dye is applied and stamped onto the fabric. This is a slow process used by specialised craft industries.

Screen printing - In screen printing a pattern is printed onto fabric through a stencil held in place by a screen. Each screen prints one part of the design in one colour. After printing the dyestuff must be fixed using steam or dry heat.

Manual flat-bed screen printing - Manual flat-bed screen printing is a slow process, done by hand. It is used by designer-makers for complicated fabric designs or for small runs.

• Mesh is stapled to a frame to make a screen.
• Masking tape is stuck to the underside of the screen.
• A stencil is made from paper.
• The stencil is placed under the screen but on top of the paper.
• Ink is poured at one end of screen.
• A squeegee is used to press down and draw ink across screen.
• The screen is carefully lifted.
• The print is checked before the process is repeated.

Industrial flat-bed screen printing - Industrial flat-bed printing automates this process, with the fabric moved through the machine on a conveyor belt and the print repeating rapidly.

Rotary screen printing - Rotary screen printing uses CAD and roller squeegees. One roller is used for each colour. This is a very fast process used in the continuous printing of furnishing and clothing fabrics.

 

Joining

Textile materials are joined by stitching, fusing or heat-sealing.

Stitching - Stitching two fabrics together produces an unfinished seam. Finishing the seam prevents fraying and produces a hard-wearing, neat finish.

Fusing - Fusing is used to permanently join two fabrics together using an adhesive resin.

• Fusing by hand is used to join Vilene to fabric to make it stable and strong. It is also used to reinforce and strengthen fabrics for garments, bags and accessories and allows hems to be turned up without stitching.
• In a factory there are two types of machine used for fusing. A flat-bed press is used to join short fabric lengths for batch production, and a conveyor press is used for fusing long fabric lengths for mass production.

Heat-sealing - Heat-sealing is used for synthetic fibres made from thermoplastics, such as polyester or nylon. It is used to set a material into a shape, e.g. pleats. It is also use to seal the seams on tents and all-weather gear to make them waterproof.