RALEIGH – Drop by drop, researchers at North Carolina State University printed ink onto cotton fabric to create a “digital” denim fabric that looked like six different styles of jeans. When interviewing a team of textile experts, they found that overall, the samples taken with the computer and printer were on average a good match for denim made using traditional methods and more. labor intensive.
However, in the Journal of Imaging, Science and Technology, Researchers reported that some styles of jeans were easier to reproduce using inkjet printing than others, and some characteristics, such as color, were more easily reproduced. With further study, the researchers said they expected digital printing to be a viable method of making new denim products in the future, with less waste.
The abstract spoke with the co-author of the study Lisa Chapman, associate professor of textile and apparel technology and management at NC State, and senior author Ming Wang, former NC State graduate student, on the study.
The abstract: Why did you get interested in digital jeans printing?
Chapman: Denim is a staple of our wardrobe. Almost everyone has several pairs of jeans in their closet. It is a very popular article. It is also one of those clothes that are sold all over the world. But the denim manufacturing process consumes a lot of water. One of the things the industry is looking at is, how do you reduce the amount of water used for denim?
Wang: To make jeans, the cotton yarn is dyed, then there are finishing and washing processes that give the jeans a certain look. These processes can have many negative impacts on the environment, such as water pollution and energy consumption. I wanted to explore another way to produce the same look of denim that is more environmentally friendly.
AT: What is inkjet printing? Why is it used in the manufacture of textiles?
Chapman: Inkjet printing is really similar to your home inkjet printer in that it will project ink droplets onto the fabric. But in this case, it deposits textile dye on the surface of the fabric.
We consider this to be an emerging technology as it still represents a relatively low market share in textiles. But it has potential mainly because it uses less water, less energy and it’s a print-on-demand process. Thus, you eliminate certain steps in the coloring process and you have an unlimited number of colors. To print using the traditional process, as you increase the number of colors, you increase the cost of the design. Inkjet printing is not like that; 200 colors equals two colors in terms of cost.
At one point in the history of clothing and furnishings, we had a lot of the same products. We would print a lot of yards of the same design. We have now moved to a group of consumers who demand a lot of variety. When you have a lot of variety you have more prints and you have smaller production runs and screen costs can be very high. Inkjet printing becomes more profitable.
AT: In your experiment, how did you create digital denim?
Wang: I used a high resolution scanner to scan a very high resolution image of the jeans samples, then transferred it to a computer file that could contain the color and transparency information. Next, I chose a pretreated fabric that has the same weight and texture as the traditional jeans samples. In the digital printing lab, I had access to four different inkjet printers. After struggling to find the right ink and the right printer, I chose the latex printer, which is more environmentally friendly. I chose six different types of denim that have different washing effects. We have discovered that digital printing can reproduce all of these effects.
AT: What did the expert panel say about the digital quality of denim?
Wang: We found 12 textile industry experts who have a lot of experience including denim and color matching. We asked them to compare digital denim and traditional jeans samples. For color, traditional and digital denim were very close. On a scale of one to five, with one as the biggest difference, five means there is no difference, the average score for the color was around three or more than three. Which means we had a good match for the color.
Besides the color, we also rated the line quality, texture, lightness and overall match. What we have found is that it is very difficult to get the quality and texture of the line. We believe the reason could be that traditional dye has high ink penetration. But for digital printing, it’s printing on the surface of the fabric, and it doesn’t penetrate that much into the fabric. It could cause the difference in line quality and texture.
AT: What is the future of digital denim?
Wang: If someone could solve the ink penetration problem, I think we could mass produce denim products with high speed printer. It could lower the cost of production. However, since mass production is not yet completely realistic, we could use digital printing for high-end denim products such as home textiles or clothing. For kids, they get bigger every day, so you might get something that looks like jeans.
Chapman: It can be difficult to replace traditional denim, but there are other markets where it could do a much better job. Jeggings are a good example. In addition to baby clothes, there are situations where you want the denim look, but you want a higher drape and softer fabric, like dress shirts or ladies’ dresses.
AT: What is the future of digital printing for textiles?
Chapman: While there is a pretty steep learning curve for digital printing, there are also advantages with reduced power consumption, chemicals, and water waste when we compare digital printing to screen printing. The dot-com market will also boost digital printing. We will look at new technologies that speed up the production cycle to get goods to consumers faster.