The effect of viscosity on the initial buildup rate and saturation accumulation radius of Mn
2P
2O
7particles in glycerol-water solutions for single wire HGMS was studied. Experimentally, for the axial flow configuration, it was found that the initial buildup process is adequately described by a previous model,

, where A is inversely proportional to the viscosity. Experimental values for the saturation accumulation radius are described as a function of the ratio of the magnetic force to the drag force by

. These results are explained by a simple force balance model at the surface of the buildup.