Nassau Fine Art Acrylic markers are water-based colored pencils that stick to most substrates, such as; paper, cardboard, canvas, stone, plastic, glass, ceramics, textiles and metal. Is it the first time or a while since you used the pen? Shake it for 20 seconds. Gently, but firmly, press the tip vertically against a blotting paper and gently pump the tip up and down. The pens have double tips and can be painted over. Just make sure the first color has dried completely before applying the next layer.