The primary solutions for addressing "ghosting" (double imaging) in screen printing include the following:
Adjusting screen tension:
Cause: Insufficient screen tension causes the screen to deform during printing, resulting in ghosting.
Solution: Increase the screen tension to ensure the screen remains flat and stable throughout the printing process.
Adjusting the off-contact distance:
Cause: An excessive off-contact distance causes uneven pressure from the squeegee on the screen, leading to ghosting.
Solution: Reduce the off-contact distance appropriately to ensure the squeegee applies uniform pressure across the screen.
Controlling squeegee pressure:
Cause: Excessive squeegee pressure can deform the screen, causing ghosting.
Solution: Adjust the pressure settings on the printing machine to ensure moderate squeegee pressure during printing.
Increasing platen adhesive tack:
Cause: Insufficient adhesive tack on the platen allows the substrate to shift during printing, resulting in ghosting.
Solution: Use an adhesive with higher tack to ensure the substrate remains stable and stationary during printing.
Checking and securing the back of the screen:
Cause: Shifting or ink transfer (smudging) on the back of the screen can cause ghosting.
Solution: Carefully inspect the back of the screen for shifting or ink transfer, and use appropriate securing methods to prevent the screen from moving during printing.
Implementing these measures effectively resolves ghosting issues in screen printing and improves print quality.