Journal of Fashion Business Vol. 9, No. 6, pp.117~125(2005)
A Study on the dyeing of wool felt using cochineal and mordants - change of color and image analysis of dyed felt -
Lee, Jung-Min · Kim, Jong-Jun*
Doctoral Course, Dept. of Clothing and Textiles, Ewha Womans University Prof., Dept. of Clothing and Textiles, Ewha Womans University*
Abstract
Felt fabric is one of the nonwovens characterized by the entanglement of the constituent fibers, resulting from the application of heat, moisture, andmechanical action to a fibrous web. This method has been applied to the wool fibers for long. As a natural dyestuff, cochineal dyestuff was employed for dyeing felt specimens. The color of the dyed felt was measured using a colorimeter. Along with this,an attempt was made in order to evaluate the variance of the color of the felted specimens having irregular orientation of wool fibers.
Key Words : felt, mordant, cochineal, color measurement, image analysis
I. Introduction Cochineal dyestuff is obtained from the bodies of the female Dactylopius coccus. This Product development in textile-related animal produces a deep maroon pigment and industry has focused on the environment- stores the pigment in body fluids and friendliness in recent years. Therefore, natural tissues.3) Cochineal forms a very fine crimson dyeing has become one of the interesting on an aluminum mordant, and scarlet on tin topics. Red color may be obtained from oxide.4) Main component of the cochineal is various plant sources such as madder root carminic acid(C22H20O13), and a natural and related alizarin-based dyestuffs. The other anthraquinone dyestuff. It has a melting point main source of red came from insects. The of 135℃ , and is easily soluble in water, best of these insect sources was American ethanol, ether, propylene glycol, and NaOH cochineal, which provided the best intensity solution, while insoluble in benzene, and 1,2) of color and was most readily available. chloroform. Since it has carboxylic end
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groups in the molecular structures, it behaves The wool fiber is structurally complex and similar to acid dyestuffs.1)3) composed of the cuticle, the cortex and the Felting of wool is commonly used to medulla. The cuticle is composed of thin improve the properties of woolen garments or scales, comprising epicuticle, exocuticle, and materials.1) One of the definitions of felt is "a endocuticle. The epicuticle and the exocuticle textile fabric characterized by the entangled contain high amount of sulphur with cystine condition of many or all of its component cross-links having high resistance to fibers." As one form of the felts, pressed felt biological and chemical degradation along is usually consolidated by the application of with water repellency. The cuticles also moisture, mechanical action and heat.4) endow the wool fiber subtle luster, which is The CIE(International Commission on one of the important apparel textile fiber Illumination) tristimulus value system, using X, properties. YandZthatrepresentthespectrumof primary colors red, green, and blue, Leeder6) reported that the dyes have been respectively, was formulated in 1931. In the foundtoenterthefiberatthejunctions L*a*b* color system, L* is the lightness between the cuticle cells and to diffuse variable; a* and b* are chromaticity through the wool via the relatively lightly coordinates. crosslinked nonkeratinous regions, and in the RGB values of the acquired image region of later stages of the dyeing cycle, the dyes specimen may represent the distribution or migrate into the sulfur-rich keratinous regions. variance of the colors of the specimen. The previously reported data in the study of Therefore, using a color CCD camera, one dyeing differences of the cotton using canmeasurethevarianceorevennessofthe cochineal7) was also compared with the dyed specimen, in this case, dyed wool felt results from this study. specimen. The evenness measurement of the In this study, wool fiber rovings were dyed fibers, especially wool felt specimens, formed into felt specimens. The felt may be affected by the fiber configurations specimens were then pre-mordanted and including the orientation of the fibers in the subsequently dyed using cochineal dyestuff. felt, and the reflection and transmission Color of the dyed specimens were measured characteristics of the fibers, and the optical using a colorimeter. Wool fibers often exhibit density of the dyed fibers. Using conversion natural variation in color yield fiber by fiber. equations, the RGB values under specified Therefore, an attempt was made to quantify measuring conditions may be converted to the the variation of color in the cochineal dyed corresponding L*a*b* values. wool felt specimens, using a color CCD camera coupled with an objective lens. [XYZ]=[rgb][M]
118 Lee, Jung-Min · Kim, Jong-Jun / A Study on the dyeing of wool felt using cochineal and mordants
II. Samples and Experiments 2) Mordanting
1. Sample and Mordants Each 2% o.w.f. mordanting agent was added to the bath of deionized water of 1) Sample liquor ratio 1:75. Wool felt specimen was dipped in the bath at 40℃ bath temperature. The bath temperature was gradually raised Commercially available rovings of wool from 40 to 60℃ within 20minutes. The fibers of 70's were used for felting. specimens was further mordanted for 20 minutes at 60℃ , and the bath was cooled 2) Mordants down to room temperature.
Three types of mordants, CuSO ·5H O, 4 2 3) Dyeing of specimen AlK(SO4)2·12H2O, and SnCl2·2H2O(Dukasan Pure Chemical Co., Ltd.)were used for Cochineal was used to prepare dyeing mordanting. solutions of L.R. 1:75 at 30℃ . After bath was heated to reach 40℃ , cochineal was 2. Experimental Procedures introduced to the warm bath and solubilized. Specimens were dipped in the bath and the 1) Felting initial dyeing temperature of 50℃ was maintained for 10 minutes. The temperature Wool fibers were pulled from the wool fiber was again raised to 60℃ and it was rovings and placed on a plate. Three layers maintained for 20 minutes. When the dyeing were needed for the felt. The first layer has procedure was finished, the dye liquor was rows of fibers placed horizontally on the cooled down to room temperature. The dyed plate. The second layer was placed specimens were rinsed with deionized water perpendicular to the first layer, and the third and room-dried. perpendicular to the second layer. A screen was laid flat on top of the layers. Water was 4) Color measurement sprayed over the screen until the wool fibers underneath were thoroughly wetted. A The color of dyed specimens were detergent solution (Beat, CJ Lion Co., Korea) measured using Chroma-meter(CR-200b, was evenly sprayed on the wet sample. Minolta, Japan). Using the L*,a*,b* values Pressure and manual rubbing was applied on obtained, color difference(Δ E) was calculated the fiber layers to disperse the detergent as follow : solution and to further the felting procedure.
* * 2 * * 2 * * 2 ∆E = (L1 − L2 ) + (a1 − a 2 ) + (b1 − b2 )
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5) Image acquisition using By introducing mordanting procedure, it was a CCD camera and image analysis clear that dye uptake was promoted based on the E values of the Al and Cu mordanted A CCD color camera, ProgRes®C10plus wool felt specimens, while that of Sn (Jenoptik JENA, Germany), was used for mordanted specimen was relatively lower than acquiring images of the dyed specimens that of unmordanted specimen. The cochineal under illumination. color of the dyed fabric changed appreciably The CCD used in the camera wasa diagonal according to the characteristics of mordants. 8.93mm interline CCD solid-state image Sn mordanted specimen gave the dyed wool sensor with 3.24 million pixels and unit cell felt specimen bright color and the highest L* size of 3.45x3.45㎛. RGB primary color value among the cochineal dyed specimens. mosaic filters are used for color filtering. The Cu mordanted specimen gave the lowest b* CCD also employs a peltier cooling device to value, leaning toward bluish and purplish lower the electrical noise generated during the color. acquisition. From the previous study,7) theΔ E value of A magnifying lens(type 350N) was attached the unmordanted and cochineal dyed cotton to the C-mount of the CCD camera. fabric specimen was 17.48, which is visually As an image analysis tool, ImageJ(NIH, discernible, though pale. By introducing USA) was employed for histogram analysis mordanting procedure, it was clear that dye and others. uptake was promoted based on theΔ E values of the Sn mordanted fabric, while that of Cu mordanted fabric was almostsimilar to that of III. Results and Discussion unmordanted. In the case of cotton fabric specimen, the mordanting effect was not