How to tell when a batch is actually dry

The reliable test is weight: weigh a tray, run another two hours, weigh again. If the number has stopped falling, the batch is done. Everything else — snapping, cold spots, appearance — is a useful early indicator but not proof.

The four checks, in order of reliability

1. Weight has stopped falling. The only real test. Weigh your test tray, run two more hours, weigh again. No change means no more water is leaving. This is definitive.
2. No cold spots. Feel the centre of the thickest piece. Sublimation absorbs latent heat, so anywhere still cold is still actively drying. A finished batch is at room temperature throughout.
3. Snap, not bend. A finished fruit slice breaks cleanly with a crack. If it flexes, folds or feels leathery, there is moisture in it.
4. Cut one open. Sacrifice the thickest piece and look at the centre. Any translucency, darker colour or cool feel is water.

Why the timer is not on that list

Because a cycle length is an estimate the machine made from its own sensors and presets, not a measurement of your specific load. The same machine, same setting, same food will finish at different times depending on slice thickness, quantity, and how cold the food was going in.

Machines with per-tray sensors give you better information than machines without, but even those are inferring dryness rather than measuring it directly. The scale does not infer.

How to run the weight test properly

You need a kitchen scale reading to at least 1 g. Before the cycle, weigh one loaded tray and write the number down. When the machine says it is finished, weigh that same tray again. Then run two more hours and weigh a third time.

Reading	Example	Meaning
Loaded, before cycle	2,140 g	Starting point
After the cycle ends	604 g	Most water gone
After 2 more hours	601 g	3 g change – effectively finished
After 2 more hours	578 g	Still 26 g falling – not finished

When in doubt, run longer

Over-drying costs you a little electricity and, on delicate foods, slightly more brittleness. Under-drying costs you the batch three months later. The asymmetry is enormous, and the correct instinct is always to run another two hours.