TEXTILES.ORG
Proficiency in post-print finishing is a balance of art and science.
By Jeff Sanders with technical assistance provided by Mike Sanders
It has often been said that digital fabric printing is 50 percent science and 50 percent art. It is in the area of post-production finishing that this maxim is most evident. Frequently, in the process of evaluating a new fabric, one may supply test samples to several print facilities that are using identical equipment and even identical inks. Yet, when the results are reviewed, widely dissimilar outcomes are apparent. In one sample there is evidence of crocking, in another there is evidence of a pronounced bleed, and in a third there is a perfect print with crisp resolution, and a soft hand. So how would one account for the dissimilar effects?
When imperfection happens…
Time and again dissimilar results can be attributed directly to the finishing process, and in particular to the treatment of heat setting. Time and temperature should be held foremost in the minds of all involved in post treatment. Regardless of method or equipment, success or failure always comes down to time and temperature. Just as a chef understands how critical it is to bring a sauce to a boil without burning, it is equally crucial to apply heat to fabric without scorching and causing crocking, which is when color rubs off. Conversely, if there is not enough heat and dwell time, bleeding (color coming off due to water, humidity or perspiration) will occur.
Experimentation and improvisation are key factors that distinguish and separate the best printers from the competition. When it comes to fabric printing, each and every application is unique. Sometimes even the smallest procedural changes will provide significant improvements to the overall look and hand of a print. If you run the same temperature and speed on every fabric you will produce a mediocre product at best. Lightweight fabrics require less time and temperature than heavyweight textiles. Additionally, maximizing heat and speed settings can represent savings in the thousands of dollars in production costs.
Find your own “magic”
Don’t hesitate (within reason) to experiment with the recommended formulas and settings of equipment and ink suppliers. The knowledge and tricks gleaned from hours of trial and error are held jealously by print professionals who rarely share this information, even with their own print machine manufacturers or ink suppliers.
Of equal importance is the element most overlooked in post production—the wash-off. For a number of printers, wash-off equipment and the process itself is often minimized and approached in a haphazard way. High quality washers tend to be expensive. The best are designed to handle large production volumes and can easily reach a cost of $50,000 or more. Smaller print houses and specialty low-volume print facilities may have to “make-do” with equipment designed for commercial laundries and in some cases even home use.
The inherent problem with such machines is the difficulty in maintaining proper temperature levels or even being able to ascertain the true temperature, which leads to the predicament of having inks continually re-depositing onto the fabric as quickly as they are washed off.
In addition, the chemicals used in the wash-off procedure will not activate properly atlow or fluctuating temperatures. This dilemma can be reduced by locating the water heater in close proximity to the washer and using a high-quality thermometer to take an accurate reading at various steps throughout the procedure. Once again, time becomes a critical factor,as leaving fabric in the bathtoo long will also causeredeposit problems.
Fabric improvements
While improvements allowing for retrofits to existing equipment and new machine technologies will doubtlessly continue, it is advances in fabrics themselves that may produce the greatest post-production benefits. During the past year new fabric finishes have been tested that require no washing at all. The savings in production time alone—not to mention water, gas, and electricity resources—make this a rare breakthrough that promises dividends forboth the environment and the bottom line.
There are currently three fabrics—flag, poly poplin, and a poly satin—available with this finish, with many more to be in production by the year’s end. Another fabric innovation that demonstrates mill post-treatment advances is a new water-repellent fabric developed specifically for digital printing. In the past, digital printers have been frustrated in their attempts to work with water repellant textiles because ink and dye was equally repelled from the fabric surface. Now, with this new material the repellant is activated by the heat set procedure after the material has been printed. This advance will allow digital printers to compete in additional arenas such as the lucrative pop up tent market.
It’s a partnership
The combination of increasing revenue, while saving on production costs, is the essence of what drives advancement in post-finishing technology, but it can be achieved only by utilizing and trusting in the advice of your print partners. All successful printers develop individual associations with their equipment manufacturers, ink suppliers (dye or pigment), and textile providers. A new improvement in ink sets, an innovation in fabric coating, or a change to print machinery will fundamentally result in an overall profile change. Whether that change is accomplished seamlessly is dependent upon all of your print partners actively sharing information with you and each other.
While profiling is not thought of as a function of post production finishing, many post-production problems can be credited to a poor profile at the outset. No one ever decided to become a digital printer because they wished to master the challenges of post-production finishing. The art is all on the front end.
Where it really happens
Visual communication through design and color management is the exciting part of our craft, but post-production is the business end. Profit, quality, and longevity of product are all linked to proficiency of finishing skills. Long gone are the days when digital printing meant a cheap method of producing “grand opening “or “going out of business” signs. Today, our industry is at the forefront of applications as varied as architectural building wraps, home furnishings, fashion, and fine art. The inventiveness of printers working with flags, banners, point of purchase displays, and trade show markets continues to push into new niche markets.
In the years ahead our growth will come from successfully discovering ways to deliver a commodity that combines an artistic inspiration with exacting standards of quality. It will be in our ability to perfect post-production finishing that we will ensure the excellence of our products.