Wet deposition is the dominant mechanism for removing black carbon (BC) from the atmosphere, and is key in determining its atmospheric lifetime, vertical gradient and global transport. Despite the importance of BC in the climate system, especially in terms of its ability to modulate the radiative energy budget, there are few quantitative case studies of wet removal in ambient environments. We present a case study of BC wet removal by examining aerosol size distributions and BC coating properties sampled in three Canadian boreal biomass burning plumes, one of which passed through a precipitating cloud. In this plume, the largest and most coated BC particles were found to be preferentially removed, suggesting that nucleation scavenging was the likely dominant mechanism. Calculated mass absorption coefficient (MAC) in the plumes showed no significant variation, as the shifts to smaller BC cores and thinner coatings had opposing effects. Similarly, calculated single-scatter albedo (SSA) showed little variation, as a large number of non-BC particles were also present in the precipitation-affected plume. The remaining BC cores were smaller than those observed in previous studies of BC in post-precipitation outflow over Asia, possibly due to the thick coatings associated with the biomass burning particles. This study provides important constraints to model parameterisations of BC wet removal in biomass burning regions, which will help to reduce uncertainty in radiative forcing calculations.