A touch display that looks fine on the bench and washes out in a cabinet at noon is a returns problem, not a spec problem. In almost every case the culprit is the air gap between the cover glass and the TFT.
Contrast and condensation
Optical bonding fills that gap with OCA or LOCA, lifting contrast in direct sunlight and making internal condensation impossible. For a medical or marine panel that sees humidity swings, it is the difference between a feature and a failure.
One supplier, one part number
Sourcing the panel, the sensor, the bonding and the controller separately means four tolerances stacking into your problem. We deliver the chain as one tested assembly with one drawing set - which is also why our display returns run below the industry norm.