A coated plate is light sensitive from the moment it leaves its wrapping. Fogging from ambient light is gradual rather than instant, which makes it deceptive: a plate left out on a bench in a lit room will still develop, just with a degraded image that is blamed on the exposure.

Surface damage is the other loss. A scratch, a fingerprint or a drag mark on a coated face becomes a defect in the etched image, and at that point the plate is scrap rather than rework. This is what the red back film on our zinc plate is for: it identifies the coated face immediately, so plates are not stacked the wrong way round in a hurry.

Store flat, not on edge. A plate stored leaning develops a curve over time, and a curved plate does not sit flat against the artwork during exposure, which shows as an image sharp in the middle and soft at the edges.

Temperature and humidity matter for coated stock and barely at all for uncoated. Where storage is a problem — a hot warehouse, a long inbound route — uncoated plate removes the issue entirely, at the cost of the coating step.