Whenever we switch to UV inks we have problems with the non image areas of the plates staining and transfering ink to blanket then paper. Does anyone have a solution for this?
Can the tint be easily washed off the plate or is the scum difficult to wash off the plate?
gordon p
It's very difficult to wash off and it starts soon after switching over to UV.
If your problem looks something like this:
and it's difficult to wash from the plate, then, according to SunChemical's trouble shooting guide for this type of ink the problem is probably "scumming". The fountain solution is unable to keep the non-image area of the plate clean.
Their suggestions are:
1) Ink rollers are of the wrong durometer (too hard or soft) - Check durometer, setting, and condition of ink rollers.
2) Ink or dampener rollers are set too tight. - Check and reset rollers.
3) Blanket is overpacked or not tight. - Correct packing and re-torque blanket.
4) Prolonged use of oily wash-up solutions has occurred. - Change to fresh wash-up solution.
5) Plate is not properly sensitized. - Consult with prepress dept.
6) Fountain solution is out of balance. - Drain pans and tanks. Refill with fountain solution of correct pH and conductivity.
7) Ink film is too heavy. - Change to stronger ink and/or consult with your ink vendor.
8) Roller train temperature is too hot. - Maintain 80° to 85°F surface temperature on oscillators.
9) Fountain solution is too hot on press. - Maintain fountain solution at 60° to 65°F in press pans.
10) Blanket is glazed. - Remove glaze or change blanket.
best, gordon p
Do you do a good Conventional/UV ink roller conditioning when switching your press to UV inks. Are your rollers covered in Chameleon Rubber compounds meaning they will work with Conventional/ Hybrid or UV inks. Same with your blankets.
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