Up to 60%, according to the manufacturer. Inversion agitation needs enough liquid to cover the film completely; roll the tank on its side and a shallow pool reaches every part of the reel as it turns.
In real numbers, a two-reel Paterson PTP115 needs 350ml per step. Mix one litre of a C-41 kit and that is two rolls several times over.
| Tank | Rotary volume (135/120) |
|---|---|
| 1-reel PTP114 | 250ml |
| 2-reel PTP115 | 350ml |
| 3-reel PTP116 | 450ml |
| 5-reel PTP117 | 650ml |
| 8-reel PTP118 | 950ml |
Less chemistry also means less waste to dispose of. C-41 and E-6 kits have a limited life once mixed, so being able to work in small volumes is a real saving rather than a theoretical one.
The AGO Film Processor supports both rotary and stick agitation, but the chemistry saving and time compensation both apply in rotary mode.