Chapter 22 Color What three things are required for color to be perceived 1 The light source shines on the object 2 The object selectively either absorbs or transmits part of light illuminating depending on the material 3 The light enters the eye of the observer and stimulates the sensation of what we call the color of the material What are some of the problems with colors 1 Fading color lightens 2 Bleedings color moves to another object usually in water laundry 3 Migrating colors moves from one part of a garment to another by capillary action 4 Frosting loss of color due to abrasion 5 Crocking transfer of color form one material to another by rubbing What is the difference between dyes and pigments Dyes are substances that add color to materials by being absorbed natural synthetic dyes Pigments are substances that add color to materials on the surface and are not absorbed What are the different stages at which coloration can be applied to textiles Which are the most and least expensive What are the advantages and disadvantages of each 1 Fiber Dyeing Final Exam Review Mass coloration addition of color to manufactured fibers before they are extruded Solution dyeing dye is put into fiber solution and extruded as part of the fiber The color is permanent The bundles of fibers are dyed in a dye bath after fiber formation or natural fibers are dyed before used in yards or fiber web Generally wool fibers are stock dyed rather than yarn or piece dyed Advantages Disadvantages Color can be permanent if solution dye however it can be more expensive to produce The loss percentage is higher than other stages of dyeing and it is more risky for manufacturer than other stages of dyeing If fashion changes then the color can t easily be changed CTE1401C 2 Yarn Dyeing Yarns are dyed before making into fabric Next most expensive but less risky Yarns are typically dyed a solid color in a bundle called a hank or skein Individual yarns are dyed and then woven into a fabric called gingham Yarn dyed fabrics usually look the same on the front and back Most plaids and stripes are yarn dyed Package Dyeing yarn would onto perforated tubes and the dye is circulated through the tubes to ensure yarns have maximum contact with dye Space Dyeing dyed different colors along the length of the yarn 3 Piece Dyeing Material is dyed a solid color in the fabric stage The fabric is immersed in a dye bath This is the least expensive way of dyeing If the fabric is just one fiber content such as 100 cotton 100 polyester etc the fabric can be piece dyed easily However if it s a blend of 2 or more fibers that are different fiber contents that don t take the same type of dye adjustments have to be made Can be produced quickly and in mass quantity There are different methods of piece dyeing 1 beck dyeing the fabric is in rope form places little tension on fabric loop of fabric pulled in out of dye bath allowed to accumulate in bottom of beck to increase time in bath frequently used for wool fabrics and knits 2 Jet dyeing propulsion of dye liquor through fabric improves dye penetration 3 Jig dyeing stationary dye bath with two rolls above dye bath fabric rolled back forth through dye every 20 minutes or so 4 Product Dyeing 5 Paddle Dyeing Dyeing is done after product is made such as towels bed linens jeans t shirt carpets All parts must be compatible with dye type Can be done quickly without a large storage of inventory Final Exam Review Garments are usually placed inside bags to avoid entanglement Paddle keeps textile products and dye solution in motion changing directions periodically CTE1401C What is the difference between union dyeing and cross dyeing Union Dyeing is making a fabric with different fibers a solid color The fibers of different types are dyed in the same dye bath This is the only type of piece dyeing Polyester and cotton are the most common type of blends The company has to mix 2 different types of dye so that it will come out a solid color Cross Dyeing is making a fabric with different fibers 2 or more colors Know that different fibers take different dye types cellulose protein synthetic Dyes used for Cellulosic Azoic dyes good colorfastness to laundering bleaching and light They are primarily used on cotton fibers Direct dyes applied directly in hot dye solution It is water soluble and the common salts help stabilize the rate of dyeing It is inexpensive with poor fastness to laundering Vat dyes insoluble in water By chemical reduction it is converted to soluble form When it is applied it penetrates the fibers and converted back to insoluble form Colorfast to laundering and light It is expensive and has environmental concerns Sulfur dyes produce mostly inexpensive dark colors It is applied to textiles in soluble form and then oxidized to insoluble form within the fiber Good colorfastness to laundering and fair colorfastness to light Reactive dyes dyestuff reacts chemically with fiber It is easy to apply to a wide range of colors and good colorfastness to laundering Dyes used for Protein Fibers Acid dyes react chemically with fibers and colorfastness varies depending on color fiber Chrome or Mordant dyes applied with a metallic salt that reacts with dye molecule to form insoluble dyestuff It is effective for dyeing wool and silk It has excellent colorfastness Dyed used for Manufactured Fibers Basic dyes charged amino groups that are attracted charges groups in fibers They produce bright colors and the newer developments have better colorfastness Disperse dyes sparingly soluble in water The particles of the dye disperse in the water without dissolving but rather dissolve in the fibers It caters to a wide range of colors and has good colorfastness to laundering Fume fading Chapter 23 Textile Printing Final Exam Review What is printing Printing is applying pigment to specific areas of textiles It can also be used to apply resist bleach adhesive or burnout paste CTE1401C What are the four printing methods discussed in class How are they different from each other 1 Direct creation of a colored design by applying a dye or pigment directly on a textile yarn or fabric The fabrics usually have prominent color on the front and less color shows on the back There are different techniques o Block printing has a design drawn on the flat side cut away spaces between design to make raised pattern color applied to surface of block block is pressed onto color o Blotch printing both a color background and design motifs are