A trigger pump sprayer in combination with a liquid dispensed from the sprayer. The sprayer is suitable for dispensing liquid from a reservoir, through a nozzle into particles. The trigger sprayer provides for efficacious particle size distributions of the liquids, when sprayed under non-ideal conditions. Non-ideal conditions include only partial strokes of the trigger, rather than full strokes and relatively slow trigger strokes. The trigger sprayer advantageously delivers a particle size distribution suitable for liquids having particular rheological properties. The advantageous particle size distribution difference is accomplished by using a precompression piston which reciprocates in response to trigger strokes, and selecting a liquid having appropriate properties to correspond to the trigger pump operating characteristics.