March '15

For the Business of Apparel Decorating

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20 1 5 M A RC H PRINTWEAR | 91 color change is a factor as well as complete exposure on presensitized emulsion. With rapidly changing stencil technol- ogy, many emulsion and direct-to-screen manufacturers offer printable calculators for the growing number of direct-to-screen machines. Most calculators range from $35 to $100. LASER TEMPERATURE GUN It's amazing that this isn't standard equip- ment for every press and dryer. While a laser temperature gun has only one function of reading the surface temperature, it's a valu- able tool for reading platen and flash tem- peratures as well as spot checks at the end of the dryer for the surface ink film tem- perature. Keep in mind that the laser temperature gun only reads the surface temperature and not the total ink cure. Once a dryer is set correctly for a proper cure of the total ink film, you can use the temperature gun for spot checks during the print run. If the ink film cures at 330 degrees F, the surface tem- perature of the ink should read 340 degrees F or higher. Using the temperature gun throughout the day alerts you of any changes in the surface temperature of the garment. From there, you can make the necessary dryer adjustments to ensure proper curing tem- peratures. DOUGHNUT PROBE I see a great need for this tool more every day. A doughnut probe is the best way to check the precise cure temperature of the ink while ensuring it stays in the correct temperature range and doesn't move into higher temperatures. This becomes more important with the increased use of polyes- ter, poly blends, and performance wear be- cause of the dye migration issues that come with these garments. The doughnut probe is placed in the ink with wires also directly in the ink, which allows it to measure the temperature of the ink film as it moves through the dryer chamber. You can watch it reach the tem- peratures and how long it stays at each in the proper cure range. If it's too high or too low, make the necessary adjustments to your dryer. But the best value of a doughnut probe is the ability to map your dryer. The dough- nut probe monitors the temperature every five seconds and plots it on a graph, show- ing the curve of the dryer temperature. This illustrates how long it takes the ink to reach the desired temperature and how long it stays at the proper cure temperature. You can also monitor any heat spikes or drops in the dryer chamber by checking each side of the dryer belt as well as the middle of the machine for fluctuations. This shows the consistency of the dryer and points out any possible problems, such as a faulty panel or blower. Mapping the dryer is one of the best forms of quality control and assurance of proper curing, and using a doughnut probe should be a standard oper- ating procedure on every job. With these four tools, any shop can take control of the variables and take the guess- work out of screen printing. For a small investment, the proper use of these tools can bring increased quality and better time management, leading to profitability. pw An exposure calculator takes the guesswork out of exposure times. (Image courtesy KIWO)

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