formed in a plurality of steps such wrinkling is avoided therefore slitting device 33 has a rotatably mounted blade 34 which slits the surface 84 at a first lateral position to a first predetermined depth in order to insure that the surface is in fact cut and not merely creased blade 34 is rotationally driven by for example electric motor 35 by means of transmission chain 36 blade 34 is rotatably mounted on arm 37 which is connected to linkage 38 linkage 38 and hence blade 34 may be vertically positioned by air cylinder 39 to vary the depth of penetration into the laterally extending surface of the partially cured mat a second cutting blade 42 is mounted on the front of platen unit 40 unlike its counterpart however blade 42 is rotationally locked in position to provide a slicing action to the mat as it passes the blade may be adjusted by means of turnbuckle 44 directly beneath blade 42 is a journaled support roller 46 which insures cutting rather than deflecting of the mat unit 40 primarily consists of upper and lower platens 50 and 48 these platens have generally uniform cross sections which conform to the desired final configuration of the lower and upper laterally extending mat surfaces 82 and 84 fig5 platens 48 and 50 have tapered infeed sections 52 and 54 to facilitate mat entry in addition rollers 56 and 58 which are positioned adjacent the entry to the platens further compress the fibers in the mat from the dimension they had when exiting from the searing roll unit 10 mat pulling unit 60 comprises first and second endless belts 62 and 64.