A challenge that our clients commonly come across when they're doing sleeking (applying digital foil over toner) is 'picking'.
Picking happens when the foil separates from the toner before it has the chance to bond properly. It's especially common on fine detail, for example, scripted font, detailed text, etc.
To avoid this, we recommend using bearer bars.
Bearer bars can either be a 100% K picture frame border printed around the outside edge of the sheet, outside the crop mark area, or 2 strips of 100% K printed on the lead and tail ends of your sheet (again, outside the crop area).
These bars provide a good, wide surface for the foil to bond through, and keep it taut so it doesn't separate from the sheet before it gets to the release bar at the back of your sleeking device.
By the time the foil arrives at the release bar and is stripped away, the detailed areas on your sheet should be perfectly foiled with no exposed toner.
There is more than one cause of picking, so if you're still having trouble, check out this video or contact us at firstname.lastname@example.org.