Fingerprint oil can be applied in three ways

There are three ways to apply fingerprint oil: hand-applied (simple, low cost, poor effect, uneven) machine-applied (moderate cost, moderate effect) electroplated (good effect, high cost)
The fingerprint oil currently used on tempered films has a retention time of around 3 weeks when applied by hand, 1 month when applied by machine and 2-3 months when applied by electroplating. Fingerprint oil will fade and eventually disappear with more wiping.