Apparatus for the wet processing of photographic sheet material

An apparatus for the wet processing of photographic sheet material having a thickness of 0.05 mm to 0.5 mm comprising at least one treatment vessel (12, 12', 12") having upper and lower openings (17, 18), one of said openings (17) constituting a sheet material inlet and the other of said openings (18) constituting a sheet material outlet, said inlet and outlet defining there-between a substantially vertical sheet material path (20) through said vessel, said vessel including a sealing arrangement at said lower opening comprising a rotatable roller (28) biased towards a reaction surface (30) to define a roller nip (36) there-between through which the sheet material path extends and a stationary sealing member (38, 39) bearing against said roller in sealing contact along its length to retain treatment liquid (24) in said vessel (12), said roller (28) comprising a core (32) carrying a covering (34) of elastomeric material, the ratio (.phi./L) of the maximum diameter (.phi.) of the roller to the length (L) thereof being at least 0.012.