Chapter 24 Physical and Mechanical Finishes Aesthetic Finishes affects APPEARANCE or hand of the textile Functional Finishes Affects PREFORMANCE of textiles o Often not visible o Examples o May be topical only on the surface OR absorbed Wrinkle resistance fire resistance water proofing antistatic Classification of finishes o Permanent lasts lifetime of product o Temporary removed after 1 2 launders Fibers that can be heat set permanently o Synthetics o Durability usually have certain lifespan and involve resin chemicals or mechanical treatments o Many thermoplastic fibers may be stabilized through heat settings Through enzyme treatment durable finishes can be applied to a natural fiber o Enzyme treatment cellulose enzymes are used in finishing cotton rayon and lyocell to produce smoother surfaces a softer hand and lower pilling PROCESS the enzymes degrade cellulosic fibers on the surface of the fabric and mechanical action removes the weakened fibers from the surface 1 Finishes that can be applied at home by consumer o Hand builders make fabric feel thicker stiffer crisper o Fabric softeners coats yarns to allow some slippage feel softer Calendaring o A mechanical finish Types of calendaring o Schreinering o Passes fabric between series of two or more rollers o Purpose smooth fabric or create interesting surface effects Flattens yarns Examples damask cotton sateen o Friction Calendaring Glazing Fabric saturated with starch or resin chemicals Dried slightly Polishes fabric Fed into machine with rapid moving heated roller 2 Produces fabrics with soft luster and soft hand One of the calendaring rolls embossed imprinted with 250 fine diagonal liners per inch Examples of fabric Chintz or polished cotton natural cellulosic fiber o Embossing calendaring Embossed effects if a calendar roller has a raised or lowered design engraved on it Pressing a pattern onto fabrics PERMANENT when applied to thermoplastic fibers DURABLE when applied to fabrics with resin treatment TEMPORARY on other fabrics o How fabric is Cired and what it is Cired the wet look High surface polish Effects on natural fibers or rayon are produced with waxes and thermoplastic resins Heat sensitive synthetics are given a permanent wet look when the thermoplastic fibers FUSE slightly under the HEAT of the rollers o Fabrics can be polished by glazing or cire ing o Moir Also know as wooden grain for its wooden appearance Technique mostly applied to RIBBED fabrics fabrics with unbalanced weaves with many small yarns crossing over fewer large yarns 3 Taffeta medium weight weave from filament yarn used for evening wear Faille prominent rib with fine filament yarn warp and heavy spun yarn filling Two lengths of same fabric placed face to face with one slightly off grain Enormous pressure by smooth moir rollers o Embossing can be made permanent when applied to thermoplastic fibers Fabrics made from staple fibers may be brushed to remove loose fiber from fabric surface o Brushing o Napping Brushed denim Brushed tricot Many napped and pile fabrics are brushed in way that nap or pile runs in same direction Fiber ends are brushed up onto fabric surface to achieve deeper pile Usually made from fabrics with LOW twist yarn Machine with hook like projections catch fiber and pull them to surface Napped fabrics Blankets sleepwear sweaters warm active wear o Dimensional stability in fabrics Means little shrinkage 4 Wool cotton rayon have LOW dimensional stability because SWELL more in water o Fulled milled wool Fabrics are fulled milled to give more compact structure Fabrics are subject to mechanical action in presence of moisture with moderate heat Machine circulates a rope of fabric between boards RESULTS gives wool more compact structure o Fulled wool is DIFFERENT from felt because fulled wool is a CONTROLLED felting operation Wool cloth may be milled fulled to a greater or lesser degree depending on desired characteristics of resultant fabrics Milling action tends to begin slowly then increase in effects Summary Points of Chapter 24 Fabrics undergo finishing to change aesthetics and performance Finishing can be mechanical or chemical and can range in durability Mechanical finishes that change the surface characteristics of fabrics o Calendaring o Embossing o Napping Mechanical shrinkage control o Fabrics may shrink when wet depending on fiber and construction 5 o Mechanical process can be used to control relaxation shrinkage o Special processes have been developed to relax or set wool fabrics o Thermoplastic fibers can be stabilized by heat setting Chapter 25 Chemical Finishes Functional finishes o Wrinkle resistant o Fire resistant o Water proofing o Antistatic o Antimicrobial finishes Resin is a repellent retardant resistant meaning SLOWS DOWN process i e burning or wetting Proof water proof means COMPLETELY blocks process i e burning or wetting Wrinkle resistant finishes o Used mainly on cellulosic materials o First available in US in late 1940s but more widely used in 1960s o ADVANTAGES of wrinkle resistant finishes Garments are wash and wear require little or no ironing Makes fabrics more dimensionally stable reduces shrinking 6 o DISADVANTAGES of wrinkle resistant finishes Fabric is less abrasion resistant likely to fray or crock Difficult to alter clothing old hems and seams wont iron out and new ones wont press well Fabric softeners o Work by COATING yarns to allow some slippage and feel softer o Reduce static by covering yarns in oil o DISADVANTAGES Can make oily stains on polyester Reduces absorption Fire triangle o In order for fire to be present it must have 3 elements Oxygen fuel and heat Other functional non visible finishes that can be applied to fabrics o Antistatic o Sun protective o Anti mildew rot o Antibacterial microbial finishes 7 Because flammability of textiles is an important contributor to serious injuries and loss of life and property in fires there are more regulations about flame resistant finishes than any other finish Text Book Summary Points Chemical finishes are used widely to add value to textile products o They are mostly applied to padding or curing o Low wet pickup methods save energy Wrinkle resistant finishes are applied to cellulosic fabrics o Most common commercial finish is DMDHEU o Finish can be cured before or after final products are constructed Chemical finishes can render wool fabrics washable Hand builders softeners and enzyme treatments affect fabric hand Chemical finishes can alter