A study of the effects of particles on the manner in which sheets of aqueous suspensions wetted particles disintegrate during atomization by hydraulic pressure nozzle showed that the sheet stability is reduced by particles in the region where the particle size is greater than the sheet thickness due to localized thinning of the sheet due to curvature variations caused by particles moving apart in this region. At high-volume fraction of solids, the sheets perforate. It is inferred from the mechanism that the critical volume fraction of solids at the onset of perforation decreases with decreasing particle size, decreasing density and surface tension, and increasing viscosity of the medium. A critical perforation number, A(c), is inferred from the above mechanism. Waves are observed on the sheet at positions closer to the nozzle which would be absent on aqueous sheets similarly produced but free of particles. (C) 2010 American Institute of Chemical Engineers AIChE J, 57: 2007-2024, 2011