sloping panels 32 and 35 are angled toward one another but terminate before they meet thereby defining an elongate slot 38 extending axially along the bottom of the chamber sloping panels 32 and 35 are provided with respective downwardly extending flanges 42 and 45 along their lengths resilient skirts 47 and 50 are affixed to flanges 42 and 45 along their respective lengths and extend downwardly to contact the pulp mat along its axial dimension resilient end flaps 52 and 55 extend the width of slot 38 and together with skirts 47 and 50 provide a continuous sealing structure about the entire perimeter of slot 38 skirts 47 and 50 may be attached to their respective flanges in any convenient manner fig1 and 3 show a mounting using bolts thus skirt 50 is attached to flange 45 by a plurality of bolts 56 and wingnuts 57 perforated rigid strip 58 between wingnuts 57 and skirt 50 provides a relatively uniform fastening end wall 28 is fitted with mounting bracket 60 which engages screw jack 65 jack 65 is affixed to support bracket 70 mounted to the fixed structure supporting rotary vacuum drum 15 a similar arrangement including jack 75 at the other end allows the height of washer 10 above pulp mat 12 to be adjusted so that resilient skirts 47 and 50 just touch pulp mat 12 along its entire axial dimension disposed within the chamber of washer 10 are vertical dispersion plates 80 and 82 and horizontal dispersion plate 85 vertical plates 80.