The objective of this study was to determine effects of mechanical and ultrasound-assisted stirring methods for varnish + components mixing on the varnish layer’s surface hardness and surface scratch resistance. The study focused on polyurethane, acrylic, and polyester varnish systems, which were applied to three distinct wood types: Scots pine (Pinus sylvestris L.), Turkish beech (Fagus orientalis Lipsky), and African mahogany (Khaya ivorensis A. Chev.). The mixing processes included mechanical stirring for 3 and 5 minutes, as well as ultrasound-assisted stirring with varying power levels (80 watts and 120 watts) for 3 and 5 minutes. The results indicated that the highest surface hardness was achieved using the mechanical stirring method for Turkish beech with polyester varnish at 3 minutes of stirring (175.10), while the lowest surface hardness was observed for African mahogany with acrylic varnish and 120 watts ultrasound-assisted stirring for 5 minutes (66.80). The highest surface scratch resistance was observed in Scots pine treated with polyester varnish using mechanical stirring for 5 minutes (0.760 N), and in Turkish beech treated with acrylic varnish using 80 watts ultrasound-assisted stirring for 3 minutes (0.760 N). Overall, the findings suggested that the ultrasound-assisted mixing method generally fell short in terms of enhancing the varnish properties compared to the mechanical mixing technique.