When sourcing art markers, the ink type is the most critical factor; alcohol-based inks are preferred for professional blending and fast drying, while water-based inks are ideal for calligraphy and children's use. You must also evaluate the nib quality, specifically looking for Japanese-made fiber or brush tips which offer superior durability and stroke control. Additionally, ensure the markers have a high ink capacity (minimum 3-5 grams) and a tight-sealing cap design to prevent evaporation and extend shelf life.