Edge lift.

How UV-DTF transfers actually fail in the field: the centre of the graphic stays bonded and the perimeter releases, so a customer catches the lip with a thumb and peels a design off a tumbler that looked finished on the bench. The edge is where handling gets a grip and where every application error concentrates, which is why a transfer supplier's own troubleshooting list reads as a list of edge faults: surface not cleaned, dust or oils under the film, a greasy, waxed or silicone-coated substrate, air pushed out from one side instead of from the centre, and a design too large for the curve it was put on. Dishwashers finish the job on drinkware, which is why the same supplier tells buyers to hand wash. None of it shows at QC, because at QC the transfer is minutes old and nothing has caught it yet. On customer-supplied drinkware the blank is not yours to write off, so the failure returns as a replacement item plus an argument about who paid for the mug.