The terms “off-contact,” “snap-off,” and “peel-off” are commonly misunderstood and a source of confusion for printers striving for excellence in their trade. Here are the basic definitions of these terms:
Off-Contact: The distance set between the screen and the substrate before printing.
Peel-Off: The controlled lifting of the screen as the squeegee moves across the print area. Instead of the screen simply snapping back due to the off-contact distance, the automatic peel-off system actively lifts the screen, creating a precise and consistent separation angle throughout the entire print stroke.
Off-contact and peel-off are completely different and should never be used interchangeably.
The amount of off-contact needed is determined by the screen’s tension. Nothing else should be used to measure it. As we all know, the separation of the screen from the substrate is critical. This ensures that the screen only touches the surface when the squeegee presses it down. (This may differ when using special inks on soft, absorbent materials.)
We say they “should never be used” rather than “can never be used” because sometimes off-contact is used instead of peel-off due to some manual and automatic presses not being equipped with peel-off functionality. Additionally, screens can be so loosely tensioned that even using the maximum amount of peel-off isn’t enough.
Off-contact printing cannot produce an absolutely identical print due to screen flex, screen stretch, and the flexible qualities of the substrate. To mitigate this, you need to use the lowest off-contact distance possible. Using more than the minimum risks throwing off registration. We suggest an off-contact of 1/16” (1.5 mm) and no more than 1/8” (3 mm), regardless of the frame size.
When you have the right off-contact, you’ll achieve the best results. If your off-contact is too high, the ink won’t have enough time to transfer properly. What happens is that some of the ink will be pulled up with the screen rather than staying on the substrate due to the way a tight screen pulls back after the squeegee passes. The result is less ink than intended and poor prints.
The closer your off-contact, the tighter your screen tension needs to be. This results in the best print quality. Sometimes high tension isn’t enough, especially if it’s not consistent across the entire screen. As we’ve stated, screen tension determines the off-contact, so with the right tension, you can lower the off-contact, ultimately improving the precision of your registration and print quality.
Peel-off is determined by the ink’s consistency—for example, how smooth or sticky it is. Peel-off is also influenced by the size of the print. You’ll need less peel-off with a small image and more with a print that takes up most of the screen due to the amount of ink and its influence on the peel-off.
The peel-off mechanism synchronizes with the squeegee pass and increases the frame’s off-contact distance as it passes. This movement improves ink coverage as it “peels” the screen from the garment being printed, reducing issues associated with a higher off-contact setting and leading to a more accurate print.
In short, peel-off reduces print distortion and the need for high off-contact. If your press lacks the peel-off feature, you’ll need to adjust your off-contact accordingly, but this comes at the cost of a less accurate print. However, when you can combine low off-contact with peel-off, you’ll achieve a more precise print and more consistent registration.
If you’re using a press, automatic or manual, a well-tensioned screen with a small off-contact is your best option when no peel-off feature is available.
Peel-off shouldn’t be automatically used with a well-tensioned screen. You only need it when the off-contact cannot be set to provide good separation from the substrate. It’s important to set peel-off to the minimum amount necessary to keep your image accurate to the stencil.
We’d be remiss if we did not review the possible problems with peel-off. There are two ways a peel-off system works, and each produces different results.
When a screen is not tensioned correctly and the peel-off is not set properly, the screen fabric will move slightly in the direction of the squeegee stroke. This will cause the edges of the print to blur and ruin the print. Similarly, a screen with too much peel-off will cause issues consistent with a setup with excessive off-contact. Again, screen tension should be the only factor determining the amount of off-contact, and the ink’s thickness and ability to shear properly determine the peel-off. When adjusting these, adjust one setting at a time since they each affect the print in distinct ways.
In conclusion, if the printing machine’s peel-off system does not maintain an equal off-contact distance across the entire print stroke, peel-off becomes part of the off-contact feature because the distance between the screen and the garment increases when peel-off is used. Either way, peel-off and off-contact should be set to the smallest possible distance to keep the print registered, clear, and printing as fast as possible, which gets your jobs completed more efficiently!