Flash Curing: The flash unit should be set on "high" and be approximately 3" away from garment. It will take anywhere from three to five seconds to flash each color. Remember that you are not trying to cure the ink on the shirt. over flashing will cause its own list of problems.
This is a major part of screen printing process and is done for several reasons.
1-To enhance ink coverage or to prevent "bleeding" of the shirt color into the ink color. Print the first color onto the garment and flash it until it is just dry to the touch. Let the print cool and then use the same screen to print it again.
2-To prevent "muddy" prints. This happens in multicolor printing when one ink sits directly on top of another. The ink colors eventually will mix resulting in a muddy appearance of color. To prevent this flash after each color.
3-To avoid pick-up on the screen when printing a multicolor job. If you flash between each color, the print side of the screen will stay clean and reduce the possibility of shadowing.
4-Pre-shrink the garment before you print it. This is usually done on nylon, polyester, or 100% cotton garments where the registration is tight. Load the garment, send it under the flash and leave it there longer than what the actual flash time would require.
Curing the Print: The basic principle of plastisol ink curing is odtaining 320 degrees throughtout the entire ink deposit. The thicker the deposit if ink, the longer it may take.
A. To get started adjust your belt speed to run 60 seconds inside of the oven.
B. Select the air settings and oven rack height.
C. Applya temperture strip on a t-shirt and run the shirt through the oven. You are looking for a temperture of 320 to 330 degrees. If the temperture is to low, slow the belt down. If temperture is too high, speed the belt up. Re-run a cool test shirt until you get the desired results. You may want to do this test in the middle of your print run as well.
D. A standard quality check is to stretch your print left to right after it comes through the oven and cools. If the print does not crack then your print is mostly cured. If the print does crack it is under-cured. Slow down your belt speed and re-run the garments. An expection to this process would be if your initial ink deposit were so thin that there was not enough of an ink film to make the stretch test possible. Example: black ink on white shirted printed through a 156 mesh.
It is a good idea to continue the temperature strip testing for a good month of jobs. Record on your log sheet enough different examples so you can refer to it before each job. track the garment color, belt speed, heater height and air settings. Even after you have developed a solid base of information about the variables of each job you run you should always use the crack test just to be safe.
Note: The only way to know if a job is really cured is to wash a sample garment
