This remark refers both to the success of the wet-on-wet technique practised in the Netherlands at that time, as well as the fact that the trekschuit, which was a new invention in 1632, allowed regular comfortable transport between Haarlem and Amsterdam and made such trips to portrait painters possible.
This remark acknowledges both the effectiveness of the wet-on-wet technique employed in the Netherlands during that period, as well as the convenience provided by the trekschuit, a new invention introduced in 1632, which facilitated regular and comfortable travel between Haarlem and Amsterdam, enabling such journeys to portrait painters.