What is Off Contact? And How important is it?

8/23/2016

The Off Contact is the screen distance above the substrate before the print stroke.

The point of contact with print surface is limited to edge of squeegee and occurs only at time squeegee passes over surface of screen. Quality and resolution are greatly affected at the point of contact. 

Advantages: 
1.) Sharp Print. The correct amount of off-contact can reduce impact of viscous, cohesive ink. Plastisol ink with its cohesive quality can cause slurring or loss of definition and sharpness. This occurs when the screen sticks to the printed garment, and during the shearing process, the print slides. 
2.) Reduction of ink build-up. Because the off-contact causes momentary contact with surface, the contact is quick enough to overcome the cohesive nature of ink. 
3.) Increased printing speed. Ink shears at contact point, therefore, stroke can be faster than printing on contact. 

Considerations: 
1.)SCREEN TENSION- The higher the tension is, the less off-contact distance is needed. 
2.)FREE MESH AREA- This is the distance between ends of squeegee and inside of screen frame. The smaller the free mesh area, the less off-contact is possible. OUR RECOMMENDATION: Free mesh area 2 1/2 inches at each end of squeegee and 4 inches for color well at top and bottom. 
3.)PALLET SURFACE- The harder the surface, the less contact is needed.  

Off-Contact Rule: 
With properly tensioned screens (16 Newtons and above) and free mesh area of 2 1/2 inches on each end of squeegee, the off-contact distance should be no more than 1/16 inch, ideally 1/32 inch. 
With wooden frames, a suggested off-contact distance should be 1/16 to 1/8 inch. General Rule: Off-contact distance should always be less than 1/8 inch. 
Each screen should be low enough to allow minimum squeegee pressure to put the stencil into contact with the substrate, and high enough to keep the mesh from resting in the wet layers of ink.