tank 10 is filled with water and tile components including a binder of starch and or latex and optional constituents such as expanded perlite paper fiber a filler such as clay and glass fiber preferably these constituents are premixed before the mechanically air dispersed mineral fibers are delivered into the mixing tank 10 this premixing can minimize the exposure of the dispersed mineral fibers to the breaking and modulating effects of the mixer rotor or impeller 14 ideally the mineral fiber slurry is discharged from the tank immediately upon a desired consistency being reached the slurry is discharged from the tank 10 onto a moving screen of a wet felting machine such as an oliver or fourdrinier machine the ability to adequately disperse the mineral wool fibers from the compacted wool bales 11 in an air environment such as by mechanical fingers and with an air stream to transport the fibers pneumatically to a state where they are sufficiently disentangled and dispersed has significant advantage in the manufacture of acoustical ceiling tile the uniformity and separation of the mineral fibers by dispersion in air can result in a more open mat in a finished ceiling tile than has been practical to obtain by the water dispersion of the prior art variations in the manner of dispersing mineral fibers in air for direct use in a water slurry without significant mixing in the water slurry are contemplated by the invention various arrangements using rotating reciprocating and or oscillating mechanical fingers or tines and or air jets and or air stream can be implemented in a path from a bale receiving station to a slurry mixing tank these devices and expedients should reduce the density of the fibers to at least 2 lbs per cubic foot before they are introduced.