AbstractThe influence of viscosity, density, surface tension, volatility and apparent viscosity‐shear rate relationship on droplet‐size spectra and deposit characteristics of two mexacarbate (4‐dimethylamino‐3,5‐xylyl methylcarbamate) formulations, one oil‐based and one water‐based, was studied following spray application under laboratory and field conditions. The oilbased formulation had a higher viscosity, a higher apparent viscosity at high shear rates and a lower volatility than the water‐based formulation; application through rotary atomisers gave larger droplet sizes, more droplets cm−2 and deposits of the active ingredient ha−1 than those from the water‐based formulation in both the laboratory and field studies. Both formulations had similar surface tensions and densities and, therefore, the contribution of these properties to droplet‐size spectra could not be determined. Among the three properties (viscosity, apparent viscosity‐shear rate relationship and volatility), volatility contributed most to the deposit patterns of the two formulations.