For the Business of Apparel Decorating
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2 0 1 6 M A Y P R I N T W E A R || 93 from these specialty underbase products, there are entire ink lines offered for ath- letic/synthetic fabrics where proper heat management is crucial. SPECIALTY UNDERBASES Specialty underbases come in different configurations, all of which are intended to achieve the same goal. The underbase grays on the market are formulated with a carbon (charcoal) compound which is designed to absorb dyes much in the same way that charcoal is utilized to absorb odor. These products offer a great advan- tage for the textile printers who are faced with printing on synthetic fabrics of un- known quality or polyester fabrics which were known to have a bleeding problem. The initial underbase grays had a standard cure temperature of 320 degrees F. As re- search continued, the next generation of underbase grays cured at 290 degrees F. The greatest advantage here was the fact that when you had to print a specialty gray underbase, you could be assured that the underbase would properly cure at standard (320 degrees F) temperature. Although we now had the advantage of a product that would cure at a lower tempera- ture and reduce the potential of dye migra- tion, we still had to reach 320 degrees F to ensure that the standard overprinted colors properly cured as well. LOW-CURE INK LINES The key to minimizing the potential of dye- sublimation/migration is to minimize the heat exposure to the synthetic dyes in the fabric. Because of this, ink manufacturers are now focused on making inks that cure at the lowest temperatures possible. From the standpoint of standard plas- tisols, we currently have inks which cure at temperatures as low as 270 degrees F. There are cases where (depending on the fabric), we can curtail the dye sublimation potential but can still have the threat of dye migration. It is here where you have to have absolute control of your dryer tem- perature to ensure that the ink is properly cured while not under-curing the ink film. As with any product, you should always conduct proper preproduction testing to ensure that your inks, applications, and heat settings are in sync with the fabric you are printing to achieve quality product. SPECIALTY INKS At the lowest end of the curing range of specialty inks designed for printing on synthetic performance fabrics and dye- sublimated polyesters are silicone inks. Silicone inks cure at 250 degrees F, which is below the sublimation point of most any synthetic polyester as well as dye-sub- limated polyester. As with standard plasti- sols, silicone inks also come with specialty underbases as an insurance policy when printing on dye-sublimated polyester. Once again, you should always conduct preproduction testing to ensure that you have your variables controlled to achieve the desired results. Knowing the performance parameters of the fabrics you are to be printing on is the key to identifying the best inks and ap- plications needed to produce a successful end product. When in doubt, check with your ink manufacturer to discover which inks and techniques will work best with any given project. For years, the standard cure temperature for textile screen printing plastisol was 320 degrees F. Now, there are inks at various curing points to accommo- date a wide range of fabrics. In regard to bleed resistance, it did not take ink manufacturers long to realize that one of the keys to printing on synthetic fabrics, such as polyester where dye-sublimation was an issue, was to minimize the heat that the dyes in the fabric were exposed to. Once this vari- able was identified, the race to produce products that cured at a lower temperature was on. (Images courtesy the author)