Textiles: Printing and Dyeing

• Colour is the most important aspect in design inspiration and the perceived aesthetic value of textiles
• Colour, in its intensity, depth, and reflection, is a powerful visual element
• Fabric can be coloured by printing or dyeing

Applying Colour - Printing and Dyeing

• The development of coloured cloth is well documented throughout history
• Dyes from plants and animals date back to the beginning of civilisation
• Indigo, from the leaf of Indigifera tinctorial, provides a fast blue dye and was known in Asia before 3000 BCE
• Tyrian purple came from shellfish and was a prized, expensive, ancient dye
• Cochineal, from the cochineal beetle on the cactus plant, was originally cultivated in Mexico. Depending on mordants used, this dye gave outstanding reds and purples
• In the 21st century, dyes and pigments are mostly synthesized from coal or petroleum-based organic compounds
• The contemporary textile industry is aware of consumers wanting "just the right colour," which is affected by the current fashion or trends

Colour Fastness

• Manufacturers know customers are irritated if a garment's colour is not maintained for its anticipated life
• Colour fastness refers to how well a fabric retains its colour over time with use and cleaning
• Labels may be added to garments where colours are ‘designed to fade’

Work, Health, and Safety – Printing and Dyeing

• All chemicals need to be treated with care and common sense
• Dyestuff and printing pastes must be handled, stored and used following the maker’s instructions
• Best practices include:
• Always wear rubber gloves and a protective covering like an apron or old shirt
• Avoiding inhaling dust from dry dye powders and vapours from dye pots
• Do not eat food in the work area
• Store dyes and chemicals in a suitable place and in a suitable container
• When mixing dyes with water, always add the dye to the water, and never the other way around
• Work in a well-ventilated area
• Keep the containers and equipment for dyeing and printing only for that purpose
• Dispose of dyes carefully, considering environmental hazards

Printing

• A pigment is an insoluble, coloured substance applied to the surface of a material, usually attached by a binding material
• Printing paste tends to be quite viscous
• Printing is the textile art of applying a surface decoration design using a pigment-based paint
• Printing designs on fabric is economical way to add colour or pattern
• Printed designs can also form the basis of embroidery design work
• Printing is part of cultural and contemporary textile colouration and patterning of yarns and fabrics
• Printing enables multi-coloured patterns of intricate designs, and can be applied to yarns, fabric, or finished products

The Principles of Printing

• There are various methods of printing, but the basic principles involved are very similar:
• A printing bed is prepared using a soft resist underneath a hard surface
• A viscous printing paste is applied to the raised surface of a print tool
• The print tool is then pressed directly and firmly onto the fabric; a rubber mallet is used to ensure even contact with the textile material
• Often the printed design is repeated and aligning the print is called registration
• Printed fabric is then heat-set via steaming or ironing to ensure the print paste penetrates the fibres
• Printed fabrics are then washed to remove any debris, residue, or non-fixed colour

Direct Printing

• Direct printing is the most common printing technique, where a textile material has a design directly printed on its surface
• This can occur at fabric or yarn stage
• Types of direct printing include block printing, roller printing, and warp printing

Block Printing

• Block printing is one of the oldest methods to print patterns onto textile materials
• Blocks can be made of diverse materials like potato, wood, foam, metal, or lino where the design is carved into the block medium
• The patterns are usually hand-carved and unique
• Block printing tends to be slow and time-consuming, and aligning the repeating patterns is difficult
• Most block prints are mono-colour but several colors are achievable if needed

Roller Printing

• Roller printing is another method of direct printing and allows multi-colour printing
• It is cheaper than block printing because it is less labour-intensive
• Roller printing is a continuous mechanical process suitable for large quantities of fabric
• Rollers are engraved or etched with designs that are subsequently rolled onto the fabric to repeat the pattern
• Up to 16 colours can be used, with each roller holding a different colour
• Printed designs can be intricate and fine, which allows complex patterns to be created
• Rollers pick up colour from the colour vat, which is transferred to the etched roller
• Excess printing paste is scraped from the engraved roller by a small blade for a sharp print
• The design from the engraved roller is then printed directly onto the fabric, and the role of the blanket is to ensure a sharp print while the backing fabric absorbs any excess colour

Sublimation Printing

• Another roller printing method involves the colour being printed onto paper
• The paper print is then transferred to the fabric

Warp Printing

• Warp printing prints designs onto warp yarns, then woven with plain-dyed weft yarns
• The printed yarn produces a fabric with soft, blurry, muted-tone designs
• This process is used on taffeta, cotton, and furnishing fabrics

Resist Printing

• Resist printing uses a resist to prevent the printing paste from being applied to the fabric
• Resist printing methods include batik, stencil printing, screen printing, and Ikat

Batik

• Wax is the printing medium of batik and either stamped using a tjap or drawn on the fabric using a tjanting
• Batik gets dyed later and the process of applying wax and then dyeing can be repeated to produce different effects and colours
• After dyeing, the wax resist must be scoured and removed from the cloth
• Batik is a slow, labour-intensive manual process, requiring careful planning of design work

Stencil Printing

• Stencil printing uses a resist like acetate, plastic, contact paper, or masking tape
• The design is cut into a sticky resist paper or film, then stencilling brushes or sponges apply the printing paste and colour to the design

Hand or Manual Screen Printing

• Screen printing evolved from stencilling, and can be carried out by hand or machine
• Hand screen printing is labour-intensive work demanding excellent registration skills, especially with multiple colors
• A screen is made for each colour used in the design
• The frame is laid down onto the printing bed and a squeegee is used to force the printing paste through the designed areas on the screen mesh
• The screen must then be carefully lifted from the fabric and repositioned for the next print

Machine or Flat-Bed Screen Printing

• Screen printing can also be completed by machinery while applying the basic principles of manual screen printing
• Screens of silk, nylon, or polyester are coated with a photosensitive emulsion that acts as a sealer or a barrier to prevent the printing paste from coming through the screen
• The to-be-printed design is then photographed. Photographic plates are then made for each colour
• The photographic print is placed on the screen and exposed to light, and the residual photosensitive emulsion is then washed away

Automated Screen Printing

• The fabric is placed on a conveyor belt as a series of flat screens are positioned above and lowered automatically
• Careful positioning of the screens is required to register the print, along with small colour blocks placed along the selvedge to aid alignment
• The printing paste is forced through the screen with automated squeegees, and then the process is repeated for each colour required

Rotary Screen Printing

• The mechanisation of a rotary screen printer allows for continuous operation, unlike the stop-start of flat bed printing
• Rotary screen printing uses cylindrical screens and the printing paste is forced through the inside of the roller via automated squeegees
• Rotary screens are cheaper to produce than the copper rollers used in roller printing but the design is limited to the size of the roller, so wide fabrics cannot be printed using this method

Ikat

• Ikat resist printing binds yarns at intervals along their length
• The design is then printed or painted onto the surface of the yarn using dyes
• Designs are created on warp yarns, weft yarns, or both yarns, known as double ikat
• Double ikat requires careful planning to achieve the desired effect

Finishing and Weaving Ikat

• The binding is then removed, and the yarns are woven into fabrics
• The Ikat resist fabric has noticeable blurred or fuzzy edges where the resist has been used to design the print

Heat Transfer Printing

• Heat transfer printing requires the use of specially printed paper, and is heated without steam
• Pressure is applied over a short period of time to transfer the design to the fabric using the principle of sublimation, skipping a liquid stage
• The textile fabric does not require wetting out
• Design is printed onto paper using disperse dyes
• The printed paper is placed on the fact of the fabric and run through pressure-heated rollers, the dyes sublimate, and the print is passed onto the surface
• This process is economical, eco-friendly, and the waste paper can be recycled, as it does not require heat setting or water

Direct Digital Printing (DDP)

• Direct digital printing (DDP) prints directly onto fabric using inkjet technology and innovative CAD systems and programs
• This technology yields the best results in all aspects of design and textiles
• Reactive dyes print on natural fibres (cotton, silk, rayon, viscose)
• Disperse dyes print on polyester
• Limited to large-scale printing because DDP uses high-end specialist print machines

Other methods of printing

• DDP designs can be created on a home computer and printed directly onto fabric with bubble jet solution, or printed onto commercially prepared sheets, limited by printer’s size
• Discharge printing is completed after the fabric has been dyed, containing a chemical print paste that destroys dye molecules discharging the dye
• Usually used on dark fabrics with white designs to remove all discharge print residue and prevent paste from weakening the fabric

Dyeing

• The soluble colour applied from a solution called dye liquor penetrates and combines with the fibre, yarn, or fabric
• Dyeing applies a comparatively permanent colour to fibre, yarn or fabric via immersion in a dye bath

Types of Dyes and Fibre Types

• Direct dyes work on cellulosic fibres
• Reactive dyes work on cellulosic, wool, silk, acrylic and nylon fibres
• Sulfur dyes work on cellulosic fibres
• Azoic dyes work on cotton and some polyester fibres
• Vat dyes work on cellulosic fibres
• Acid dyes work on wool, silk, nylon, modified rayon, acrylic and polyester fibres
• Basic dyes work on acrylic, polyester, nylon and discharge prints on cotton
• Disperse dyes work on polyester, nylon, and synthetic fibres
• Natural dyes are primarily used on natural fibres

The Principles of Dyeing

• A set of dyeing principles include:
• Dissolving dyestuff in a certain amount of water, usually determined by the weight of the fabric to be dyed, creating known as the dye solution or dye liquor.
• Wetting the fibre, yarn, or fabric to help fibres swell and polymers move apart, making the uptake of dye slower and easier.
• Enhances consistency and ensures even dye uptake.
• Immersing the fibre, yarn, or fabric in the dye solution in a vessel, often a dye bath or vat.
• Can be applied as an emulsion or foam.
• Agitating the dye solution assists dye uptake.
• The dye solution loses its colour as the textile becomes dyed when migration occurs
• Dye molecules move or diffuse into the amorphous regions of the textile.
• Depend on the size of the dye molecule and the available dye sites in the fibre, and can be assisted by increasing the temperature and adding carrying agents, after which Fixation takes place.
• Good absorbency fibres dye well because they have more amorphousness and more considerable molecular dye sites.

Stages of Dyeing

• Includes:
• Pre-fibre dyeing occurs with solution or dope dyeing where the solution is pigmented prior to extrusion giving excellent results for hard-to-dye fibres.
• Fibre dyeing occurs with stock or fibre dyeing where the loose fibres are dyed before spinning, or with top dyeing, where tops or loose ropes of combed fibres are dyed which results in two-tone or heather patterning.
• Yarn is dyed via skein or beam dyeing, wrapped on cones or beams, then immersed in the vats of the dye machinery or the dyeing is circulated through the yarn giving good penetration
• Fabric is dyed through piece dyeing, crossing or union dyeing where affinity or dye resistance creates colour combinations and patterning as long as the materials are well prepped
• Product dyeing consists of solid or other finished colours with a quick response to fashion trends that is inexpensive if materials are well prepped

Batch Dyeing

• Referred to as exhaust dyeing, and can be used at any stage, fibre to end-product, and is circulated and low cost excellent for flexible selections of short terms.
• Methods of Batch Dyeing include:
  • Winch dyeing using sewn together fabrics that that immershed which allows the for good fiber penatration for light weight fabrics is one of the oldest forms of dyeing preformed on short fabric

Continuous and Combination Dyeing

• Jig dyeing can be utilized on large amount of fiber preformed as a fabric, pad dyeing is eco friendly,
• Combined dyeing involves circulation with jet dyeing, continuous dyeing involves dying yarns on the jet and paddle for product
• Machine while foam dyeing economical method and artistic, can also require resisting to prevent from the dye and inhibit

Appliqué

• The technique of applying fabric shapes to a fabric backing.
• Most fabrics, but not thick pile ones, are suitable for appliqué.
• Fabrics need to be pre-shrunk and colourfast before using
• Fusible web is good for stabilizing and preventing knit fabrics from stretching, while edges are stitched with stain, blanket, straight and or free motion stitch

Satin Appliqué

• To create, apply satin stitches around the edge of the shape (recommend: SW2.5/SL0.5), tearing the base fabric and finishing.
• When stitching around an outside corner, lower the needle into the outside edge of the corner and raise the presser foot.
• Always stabilise backing
• Reverse applique follows a reverse direction using straight stitches, creating custom embroideries and embellishments.

Embroidery

• A method of embellishing or decoration that requires stable fabric, decorative yarn and experimentati-on
• Running stitch is a simple outline stitch and is the simplest hand embroidery to learn

Other Types of Stitches

• Straight Stitch - consists of single-spaced stitches
• Back Stitch - used for outlines
• Stem Stitch - is another outline stitch, often used for flower stems
• Chain stitch - is a looped stitch to outline or fill
• Lazy daisy stitch -is a detached chain stitch
• Fly Stitch - is a Y-shaped looped stitch
• French Knot -raised stitch, and the size depends on thread
• Blanket and Button Hole Stitch - A stitch to creat border
• Couching - Stitch to create a 3d effect
• Machine - Utilizes a fabric to sew with a high decorative ability