SST SBD-800 series is a high purity solvent and has well controlled on metal ions and liquid particle. Excepting the dilution and piping cleaning, it can be treated for process improvement, such as pre-wetting: 

In case of higher viscosity resist, it is not easy to cover every place especially the serious topography while coating. The solvent dispensing before the resist, and to cover the whole wafer, it could avoid the seam/void after coating. Another benefit of pre-wetting is to reducing the resist dispensing volume.