temperatures of 80o dye performance.


C, which is an excellent achievement for


The CIE (International Commission on Illumination) L*a*b* Color Space System provides a system of coordinates which allow color to be quantified. The color difference between treated and untreated areas


of the fabric substrate was


measured using a Reflectance Spectrophotometer and the results found to be significant. By exploiting this color difference,


potential was shown for CAD controlled laser treatment to be used as a design tool/technique. Up to an optimum power density, laser parameters can be chosen to achieve a variety of mark making and gradiated tonal graphics.


Figure 2. Wool Dyeing Schematic


dyeing wool in industry, where the dyebath is held at 100 o 90 minutes. Test temperatures of only 80 o


C for C were used


throughout this study, held for a reduced overall dyeing time as shown in green on the schematic in Figure 2. When these conditions are compared, some very significant energy savings can be seen, estimated at an approximate 54 percent saving.


The results of increasing power density on laser pre-treated wool, followed by dyeing are shown in Figure 3. Visually, a change in color can be seen between each of the laser treated samples (b to e) and the untreated control (a). As laser power increases, the color change appears to show increasingly darker shades of blue.


As well as an apparent visual effect, dye exhaustion results indicated that an increasing amount of dye uptake was achieved, by a significant 9-10 percent, as the laser power density delivered to the fabric increased. More dye was accepted into the laser treated fibers, despite the lower than optimal


Geometric patterns consisting of solid, undulating and linear shapes were laser marked on 100 percent wool fabric, followed by dyeing with reactive dye. The resulting samples, shown in Figure 4, provide an all over pattern. The technique has the potential to be used on woolen textiles of varied constructions and weights, suitable for fashion or home interior applications.


When compared to the lack of current graphic capabilities of dyeing in industry, digital laser dyeing has the potential to open up a new way of patterning textiles. It is now possible to design with dye using the CAD controlled laser. High-resolution graphic capabilities can be achieved, which still meet important material performance properties.


Harmful chemical pre-treatments and further production processes could be eliminated by combining coloration and patterning in one, with an improved dye uptake resulting in a reduction in dye effluent and an approximated 54 percent energy saving using the laser technique.


As laser marking operates a remote, non-contact set up, the potential to place designs on finished products and across garment seams would allow manufacturers to customize


Figure 3. Laser pre-treated, dyed wool samples subject to power densities from 0 to 60 kW (Continued on page 14) www.lia.org 1.800.34.LASER 13


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