the fan folds 45 are produced a conveyor 44 is diagrammatically illustrated by the headed arrow associated therewith for moving the at least partially cured now fan folded mineral fiber web 43 to the right as viewed in fig1 the fan folds 45 are of course shown relatively spaced from each other but it is to be understood that the rate of movement of the conveyor 44 and the motion of the oscillating means 42 forming the fan folds 45 is such that the adjacent surfaces of adjacent fan folds and the interiors thereof are in contact the binder applied at 48 will of course prevent the fan folds 45 from expanding although any of the means heretofore described relative to fig1 can be utilized as the partially cured fan folded mineral fiber web 43 moves to the right by the conveyor 44 it encounters severing or severence means 49 corresponding identically to the severing means 6 of fig1 at this point the severing means 49 severs the partially cured fan folded mineral fiber web 43 into a relatively thin secondary nonwoven mineral fiber web 51 and another secondary nonwoven mineral fiber web 50 the two secondary mineral fiber webs 50 51 and others can of course be similarly severed from the mineral fiber web 50 the secondary mineral fiber web 51 is then treated just as the mineral fiber web 8 of fig1.