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| Posted on 5/2/08 at 06:02 AM | |
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Let's start with the flash. How did you determine heat and dwell? Do you know that a flash should heat the ink to just barely past the liquid state? When touched, it will be just past the point of coming off on your finger, probably around 250. Remember also that the dwell time or temp may need to be reduced after the boards start holding heat. Here's the blurb from an International Coatings White: SPOT FLASHING This product will spot dry, with a very low after flash tack, in 2 to 8 seconds depending on the spot dryer used. In some cases, you may have to lower the heat of the spot cure unit because too much heat may actually make the ink tacky. When you spot dry, you are only partially fusing or gelling the surface of the ink. The ink should just be dry to the touch, with no lift off, but not totally fused. Totally fusing the underprint white may cause inner coat adhesion problems with the inks printed on top of the white ink. Final fusing or curing will occur in the dryer. and from a Union ink: Curing Instructions: Plastisol inks will not air dry and must be heat cured. PADM-1027 will start to gel at approximately 240°F and temperatures, dwell time and distance of flash cure unit from print should be regulated so the underbase print is only surface dry to the touch. This ink will fully cure and withstand repeated washings when the entire ink deposit reaches 300°F (149°C). If Bright Cotton White ink is printed through coarser meshes, the resulting heavier ink deposits may require longer oven time or possibly higher temperatures. Proper curing is extremely important. Poor washability of the print can generally be traced back to undercuring. Now, if ink is coming off all of the way down to the shirt, the whole layer is not reaching cure temp of about 300-320. How are you measuring this? The actual reading from a non contact thermometer will be considerably higher than this for the instant just before exit. Probably closer to 380. ____________________ It's crackers to slip a rozzer the dropsy in snide. Remember the center crease is merely a suggestion. | |
  
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