Textile Coloration & Surface Ornamentation - Aesthetic Finishes
Aesthetic Finishes
Aesthetic finishes are treatments applied to fabrics to alter their lustre, drape, and texture, primarily to enhance their appearance and sales appeal. These finishes not only improve the visual appeal but also add value to the fabric, making it more attractive to consumers. The choice of finish depends on the desired look and feel of the final product, as well as the fabric type and its intended use.
Finishes Related to Fabric Lustre
Glossy Finish: Achieved through the application of resins or coatings, resulting in a shiny surface that reflects light. This finish is often used to create a luxurious or eye-catching effect.
Matte Finish: Gives a soft, non-reflective appearance, often desired for a subtle and sophisticated look. Matte finishes are popular for creating a more understated and elegant appearance.
Silk Finish: Mimics the natural sheen of silk through finishing techniques that smoothen the surface and enhance brightness. This finish provides a smooth and elegant look, making fabrics feel more luxurious.
Lustre refers to how light interacts with the fabric's surface. Finishes in this category aim to change the fabric's light reflectance properties, making it shinier or more subdued. Techniques include:
Calendaring: Modifies the fabric surface using time, temperature, pressure, and dampness. It involves passing the fabric through a series of rollers, which can be smooth or engraved. Calendaring is a versatile technique used to enhance various aspects of fabric appearance and texture.
Objectives of Calendaring:
Imparting a soft and smooth surface: Calendaring helps to flatten the fabric, creating a smoother texture that feels pleasant to the touch.
Adding glaze or lustre: By applying pressure and heat, calendaring can create a shiny or polished surface.
Creating a silk-like appearance: Special calendaring techniques can mimic the sheen and smoothness of silk fabrics.
Closing the yarns together to increase fabric cover: Compressing the fabric enhances its density and reduces its transparency.
Compressing the fabric to reduce thickness and air permeability: This can be useful for creating wind-resistant or water-resistant fabrics.
Flattening slubs: Slubs are thick or uneven areas in the yarn, and calendaring can help to flatten them for a more uniform appearance.
Imparting decorative surface patterns through embossing: Engraved rollers can create raised patterns on the fabric surface.
Increasing fabric opacity: By closing the yarns together, calendaring can reduce the amount of light that passes through the fabric.
Consolidating non-wovens: Calendaring can help to bond the fibers in non-woven fabrics, increasing their strength and durability.
Calendaring Machine: Typically has 2 to 7 rollers (bowls) made of alternating hard steel and elastic materials like compressed paper, cotton, or nylon 6. The arrangement ensures uniform compression. Steam circulation chambers provide heating. Controllable parameters include fabric speed, roller speed, and roller surface.
For lightweight fabrics, fewer bowls are used; for heavyweight fabrics, more bowls are used. This ensures that the appropriate amount of pressure is applied to the fabric.
Types of Calendaring Effects:
Surface glazing: Creates a shiny surface by applying resin or wax.
Cire effect: Produces a highly polished, wet look.
Moire effect: Creates a wood-grain pattern on the fabric surface.
Schreiner effect: Imparts a soft, low-key lustre.
Embossing effect: Creates a three-dimensional design.
Surface Glazing:
Glazed fabrics are produced by saturating the fabric with a starch, wax, or resin solution, drying it, and then calendaring it. The solution fills the gaps between the yarns, creating a smooth surface.
Resins provide a permanent glaze, while starch or waxes offer a temporary finish. The choice of glazing agent depends on the desired durability and appearance.
The metal roller's speed is greater than the fabric's speed, causing friction that distributes the wax or resin between the inter-yarn spaces, creating the glazing effect. This friction polishes the surface and enhances the shine.
A 10-bowl calendar is used for swizzing when high glaze and large production volumes are required. The multiple rollers ensure uniform application and a high-quality finish.
Cire Effect:
Ciré fabrics have a glossy or wet look, produced similarly to glazing but with friction rollers rotating at much higher speeds. The high speed generates more heat and friction, resulting in a more intense shine.
Fabrics are coated with wax or resin before calendaring with heated rollers. The coating helps to create a smooth surface and enhance the reflective properties of the fabric.
With thermoplastic fibers, the surface melts slightly upon contact with the metal roll, resulting in a highly polished fabric. This effect is particularly pronounced with synthetic fibers like polyester and nylon.
Suitable for cotton, rayon, polyester, nylon, and blends. The cire effect can be applied to a wide range of fabrics, making it a versatile finishing technique.
Moire Effect:
Produces a wood-grain design on the fabric surface. This effect is created by varying the light reflectance across the fabric.
Can be temporary, durable, or permanent, depending on the pretreatment and fiber type. The durability of the moiré effect depends on the specific techniques and materials used.
Methods of production:
Using engraved calendaring rollers: The engraved roller flattens parts of the fabric more than others, causing different light reflectance and creating a definite repeat pattern. This method allows for precise control over the design.
Using smooth calendaring rollers: Two ribbed fabrics are fed face to face through the calendar. The high pressure causes the ribs to squeeze into each other, resulting in random moiré effects. This method creates a more organic and unpredictable pattern.
Overlapping Colors: Overlapping different colors when printing fabrics to create a sense of depth that varies as the eye travels across the pattern of the fabric. This technique adds another layer of complexity to the moiré effect.
Schreiner Calendaring:
Produces a low, soft-key lustre, distinct from the high glaze of surface glazing. The fine lines diffuse the light, creating a subtle sheen.
The fabric is passed through a schreiner calendaring machine with a steel roller engraved with fine diagonal lines (200-300 lines per inch). Friction creates the schreinering effect. The high number of lines ensures a uniform and subtle effect.
Commonly used on cotton and cotton/polyester sateen fabrics. Sateen fabrics are particularly well-suited to this finish due to their smooth surface.
The finish can be permanent (thermoplastic fibers), semi-permanent (resin-treated but not cured), or temporary (non-thermoplastic and not resin-treated). The durability of the finish depends on the fiber type and the use of resins.
Embossed Calendaring:
Creates a three-dimensional design on the fabric using a special calendaring machine with an engraved roller. The engraved roller presses the pattern into the fabric.
The pattern is pressed into the fabric as it passes between the rollers. The pressure and heat create a lasting impression.
Durable or semi-permanent if fabrics are treated with resins and cured after embossing. Permanent for thermoplastic fibers due to heat-setting. The use of resins and heat-setting enhances the durability of the embossed pattern.
Beetling:
Produces a smooth, lustrous linen look by flattening the yarns as the fabric revolves around a drum while being pounded with hammers. This technique is traditionally used on linen to create a smooth and polished surface.
Finishes Related to Fabric Drape
Drape finishes affect how a fabric falls or hangs. Some finishes stiffen the fabric, while others soften it. These finishes are crucial for achieving the desired aesthetic and functionality of the fabric.
Parchmentizing:
Gives crispness or body to cottons using an acid wash (sulphuric acid) to make the cotton almost transparent, and permanently stiff, as in organdy. Parchmentizing alters the structure of the cotton fibers, creating a stiff and translucent effect.
Requires precise timing to prevent weakening of the fabric. The acid treatment must be carefully controlled to avoid damaging the fabric.
After acid treatment, the cloth is neutralized, washed, and calendared. These steps ensure that the acid is completely removed and the fabric is stabilized.
Can produce an all-over effect (using sheer combed lawn) or a localized effect (acid resistance substance is printed on the figures and the fabric is run through the acid bath). Localized parchmentizing allows for the creation of intricate designs.
Acid Designs:
In localized parchmentizing, an acid-resistance substance is printed on the figures, and the fabric is run through the acid bath. This protects specific areas of the fabric from the acid treatment.
The acid-treated areas become almost transparent and permanently stiff, while the acid-resistant areas retain their original opacity. This creates a contrast between the treated and untreated areas, resulting in a unique design.
Burned Out Effect:
Produced by printing a chemical solvent/acid on a blend fabric (e.g., rayon & polyester, cotton & polyester). The chemical selectively dissolves one of the fibers in the blend.
The chemical destroys one fiber (e.g., cotton or viscose) in the designated design area, leaving the other (e.g., polyester) intact. This creates a镂空 effect.
Creates a different drape property and design effect. The remaining fibers create a lightweight and patterned fabric.
Sizing:
Involves immersing the fabric in a mixture containing starches, PVA, oils, glycerines, etc. The sizing agent fills the gaps between the yarns, adding body and stiffness to the fabric.
Gelatin is used on rayons to enhance their natural luster. Gelatin provides a smooth and lustrous finish to rayon fabrics.
Fills gaps between yarns, adding stiffness, weight, and body to the fabric. Sizing improves the fabric's hand feel and makes it easier to handle.
Permanence depends on the sizing material used. The choice of sizing agent affects the durability of the finish.
Resin-based sizing with heat setting is permanent; water-soluble sizing is not. Resin-based sizing provides a more durable and long-lasting finish.
Gelatin may create water spots on rayon if not processed carefully. Special care is needed to prevent water spots when using gelatin on rayon fabrics.
Weighting:
Adds weight and body to the fabric using a metallic salt such as stannous chloride. Weighting can improve the drape and feel of lightweight fabrics.
Salts that bond with the fiber are durable; others produce a temporary surface coating. The durability of the weighting depends on the bonding properties of the metallic salt.
Finishes Related to Fabric Texture
Texture refers to the hand feel, appearance, or consistency of a fabric surface. These finishes modify fabric texture or add components that change the original texture. Texture finishes can significantly alter the tactile and visual properties of a fabric.
Softening:
Achieves a more pleasant hand feel and better drapability. Softening reduces the stiffness and harshness of the fabric.
Reduces harshness caused by construction or prior finishing processes. Softening improves the comfort and wearability of the fabric.
Can be done mechanically (e.g., calendaring - temporary) or chemically (e.g., silicone softeners - durable, requiring curing). The choice of softening method depends on the desired durability and effect.
Emulsified oils and waxes can also produce semi-durable finishes. These finishes provide a balance between durability and cost-effectiveness.
Shearing:
Evens out the length of the pile of fabric by removing surface fibers, yarn ends, knots, and irregularities. Shearing creates a uniform and smooth surface.
The fabric is brushed and passed through tension bars and over a shearing bed. This prepares the fabric for the shearing process.
Prominent fibers are cut by blades wound helically around a rotating cylinder against a stationery blade, with strong suction removing cut fibers. The suction removes the cut fibers, preventing them from re-attaching to the fabric.
Can create a smooth or patterned/sculptured effect. Shearing can be used to create a variety of surface textures.
Brushing:
Removes loose fibers and directs the nap of the surface in a single direction. Brushing enhances the fabric's appearance and texture.
Can be applied to one or both sides of the fabric. The choice depends on the desired effect.
Brushing system contains brush rolls and tension mechanisms with guide rolls. These components ensure uniform brushing.
High-pressure suction and dust collector devices clean the fabric. This removes loose fibers and dust, improving the fabric's cleanliness.
Increases the ability of the fabric to retain heat or provide a thermal barrier. Brushing can enhance the fabric's insulation properties.
Examples: brushed corduroy and brushed denim. These fabrics have a soft and napped surface due to brushing.
Napping:
Raises a layer of fiber ends (nap) from the ground weave of the fabric using wire-covered rolls. Napping creates a soft and fuzzy surface.
Examples: velvets, flannel, corduroy, and satin. These fabrics are known for their soft and napped surfaces.
Originally, dried teasel pods were used; now, pile rollers covered by heavy fabric with bent wires are used. Modern napping machines are more efficient and consistent than traditional methods.
Done on fabrics with low twist staple yarns; woollen fabrics are dampened, dried, and stretched before trimming, while cotton fabrics go straight to the shearing process. The preparation of the fabric depends on the fiber type.
Sueding:
Similar to napping but uses abrasive-covered rolls (sandpaper, emery cloth, etc.) instead of wire-covered rolls to produce a shorter pile surface. Sueding creates a soft and velvety texture.
Causes an apparent change in fabric shade and produces a softer handle. Sueding can alter the fabric's color and feel.
Plissé Finish:
A permanent chemical finish where sodium hydroxide is printed on cotton fabric as a paste. The sodium hydroxide causes the fabric to shrink in the treated areas.
The fabric shrinks where the sodium hydroxide is applied, creating a puckered effect. This creates a textured surface.
Fabrics do not require ironing. The puckered surface resists wrinkles.
When applied as lengthwise stripes, it resembles seersucker (though plissé puckers stretch out flat, unlike seersucker). Plissé is a more economical alternative to seersucker.
Plisse is a cheaper imitation of seersucker.
Fulling:
A permanent finish used in wool fabrics to improve hand feel, thickness, and appearance. Fulling involves controlled felting of the wool fibers.
Results from gradual felting of wool fabrics, increasing thickness and compactness through moisture, heat, friction, lubricants, and pressure, achieving shrinkage between 10-25. \%. The controlled felting process enhances the fabric's properties.
The fulled fabric is more compact and smoother.
Tufting:
Adds additional yarns to the fabric surface, creating a multi-dimensional appearance. Tufting can create a variety of decorative patterns.
Flocking:
Adds small, straight flock fibers to the surface of a fabric coated with adhesive. Flocking creates a pile-like surface.
Creates the appearance of a pile design or allover piles. Flocking can be used to simulate various pile textures.
Two methods:
Mechanical Flocking: Uses a beater bar system to release flocks on the adhesive-coated fabric surface, causing the fibers to stand erect randomly; excess fibers are removed by suction columns. Mechanical flocking is a simple and cost-effective method.
Electrostatic Flocking: Uses an electric charge to orient fibers perpendicularly; charged fibers are aligned with electric field lines and embedded in the adhesive-coated substrate; excess fibers are removed by suction columns. Electrostatic flocking creates a more uniform and dense pile.
Expanded Foam:
A coloured compound is printed on the fabric, which expands during further processing to give a 3D texture. Expanded foam creates a raised and textured surface.
Durable but may create problems during pressing; commonly known as rubber print. Expanded foam prints are durable but can be challenging to press.
Rubber-like substances (neoprene, nitrile, silicone, polyurethane, teflon, etc.) are coated on fabrics